Introduction
Welcome to Monster Trucks: The Science of Extreme Machines! As an educator, you have the Monster task of turning your students on to learning. We hope that this guide, in combination with the Monster Trucks traveling exhibit, helps fuel your students with a drive to learn.
The big beasts that are Monster Trucks exemplify many concepts and principles that are core components of math, physics, and auto technology classes. As a result, this guide provides a focus on three different units, so you can choose the lessons that best meet your classroom needs:
Math and Science Lessons for Grades 4 – 8 Physics Lessons for Grades 9 – 12 Auto Technology Lessons for Grades 10 – 14
All of the lessons in this guide have been designed to complement the amazing Monster Trucks: The Science of Extreme Machines traveling exhibit. The lessons are standalone, using inquiry-based and hands-on approaches that enable students to recognize real-world applications of some of the skills and knowledge that are important to your classroom goals. Additionally, many of the lessons include reproducibles for you to use as handouts or on the overhead.
Units Math and Science Lesson Plans for Grades 4 – 8 Covering a wide scope of student ages and abilities, this unit offers multiple tracks for you to take. Each lesson offers explicit suggestions on how to make it more or less challenging to better meet your students’ needs. The unit is divided into a mathematics track and a physics track — each consisting of three separate lessons.
The math lessons emphasize skills that relate directly to National Council of Teachers of Mathematics standards including: Numbers and Operations, Algebra, Measurement, and Data Measurement and Probability. The science lessons tie into the Physical Science standard (Content Standard B) of the National Science Education Standards, specifically the standard’s emphasis on Motions and Forces, and on Transfer of Energy. They also tie into Content Standard E on Science and Technology.
Physics Lesson Plans for Grades 9 – 12 The lessons within this unit build off of many concepts that are important to a physics curriculum. In order to maximize the likelihood of having lessons that would tie into your specific curriculum at the time of the exhibit, the guide presents topics that are introduced at different times within a physics course. However, because the lessons are standalone, you can use them whenever they are most appropriate for your course of study. The lessons tie into the National Science Education Standards’ Physical Science (Content Standard B), specifically to the standard’s emphasis on chemical reactions, motions and forces, and conservation of energy.
Auto Technology Lesson Plans for Grades 10 – 12+ This unit takes advantage of the similarities and differences between the worlds of an auto shop and a Monster Truck shop. By better understanding those similarities and differences, students will increase their understanding of the two themes at the heart of this section: Engines and Safety. Each of the lessons cites the NATEF Standards for Certification that apply to it, and are appropriate for intro level auto technology classes through a post- high school level program. Table of Contents
TITLE SUBJECTS GRADES PAGE
UNIT 1 Reinventing the Wheel Math 4-8 6 Data Driven Math 4-8 9 Fuel for Thought Math 4-8 12 Measures of Greatness Science, Math 4-8 15 Brain Bucket Science, Safety 4-8 18 A Matter of Momentum Science 4-8 20
UNIT 2 Monster-Sized Mechanics Physics 9-12 26 Energy: It Has to Go Somewhere Physics 9-12 30 Tons O’ Torque Physics 9-12 33 The Physics of Combustion Physics 9-12 36
UNIT 3 Engine of the Beast Autotech - Engines 10-12+ 40 A Monster Truck Engine in My Car? Autotech - Engines 10-12+ 43 Safety is Our Goal Autotech - Safety 10-12+ 45 A Safe Ride Anywhere Autotech - Safety 10-12+ 48
Glossary 50 Additional Resources and Web Sites 52
REINVENTING THE WHEEL
Objective: Students will measure, calculate, organize, and present diameters and Important Terms: circumferences to predict which household objects will roll the farthest. circumference, diameter, pi, radius Curriculum Connection: This lesson is an excellent way to introduce less advanced/younger students to Exhibit Link: circumference and reinforce measurement and calculation skills. Prior knowledge of the concept of diameter is necessary. By calculating the circumferences of a This lesson is designed variety of cans, lids, and/or other round household objects, students will predict as a pre-exhibit activity which objects will roll the farthest when traveling at the same speeds. They will that will prepare then test their predictions by rolling the objects on a single, uniform surface. students for the sight Students should conclude that vehicles with wheels of greater circumferences— and significance of the such as Monster Trucks—travel greater distances than vehicles with wheels of giant terra tires that lesser circumferences when speeds are equal. define Monster Trucks.
Class Time: 45 minutes
Materials Needed: pencils notebook paper reproducible rulers tape measures circular objects (such as different sized cans) black felt-tip markers calculators (optional) stop watch (optional) large ramp (optional)
Lesson Steps: 1. Using the reproducible, read about and discuss the Monster Truck tires. Using rulers, students should measure the diameter of the Monster Truck tire illustration. Write either the exact or approximate diameter on the board, depending upon your students’ calculation skills. 2. Define circumference and pi, either as an introduction to or review of the terms. Ask students to multiply the illustration’s diameter by pi (either 3.14 or 3, depending on your students’ abilities). Inform students that their product is the illustration’s circumference. Additionally, students can figure out circumference if they know only the radius: C=2·pi·r. 3. Introduce the circular objects with which students will be working (either individually or in small or whole-class groups). Ask them to predict which object or objects will have the greatest circumference. 4. Using tape measures, students should measure the diameter of each object. Students should measure each object at least twice to make sure their measurements are accurate. Students should record diameters on notebook paper. 5. Using calculators or pencils and paper, students should multiply each recorded diameter by pi and record the product as its circumference. 6. Students should organize and present their data in a table either independently, in small groups, or as a class (depending on students’ data presentation skills and whether all students are working with the same or identical objects). The table should include the following subtitles or fields: Object Diameter Radius Circumference
6•GRADES 4-8 ★ UNIT 1 ★ MATHEMATICS 7. Using the table, students should predict which object will roll the farthest (again, assuming speeds are equal) and, therefore, will make the best Monster Truck wheel. 8. To conclude the activity, allow students to test their predictions by rolling some or all of the objects they have measured on a single, uniform surface. The ideal surface is something like a ramp with a slight (10%) incline, so that students do not need to worry about rolling the objects at constant speeds. If a ramp is unavailable, a flat surface such as a classroom floor or basketball court is fine. Students, for example, could start with two tin or aluminum cans—one 16 ounces, the other 8 ounces. Using a black felt-tip marker, have a student make a visible mark on each can, then roll each can down the ramp. Students should count at least 10 revolutions (marking where the can finished its 10th revolution) and then measure the distance it traveled during those 10 revolutions. Have students repeat the process using the other can. Make sure that students start with the marks in similar positions, e.g., straight up. To decrease the likelihood of errors, have students repeat the process at least once. Students should see that the object with the greatest circumference has rolled the farthest after 10 revolutions. If students are unable to roll their objects down a ramp, discuss ways that they can roll the objects with constant speeds. For example, the same person should do the rolling, and the follow through on the roll should be uniform.
Academic Extensions/Modifications: ELEMENTARY AND MIDDLE SCHOOL: To extend Step 5, have students use tape measures to measure each object’s circumference and compare these measured circumferences to the calculated circumferences. To extend Step 6, have students include a field in the table in which students enter the quotient of each object’s circumference divided by its diameter. It should always equal about 3 (or pi). To extend Step 8, students in upper level classes can collect data to plot distance versus time graphs either manually on graph paper or on graphing calculators. The slope of the distance versus time graph is the speed of the object.
• 7 MONSTER TIRES! Monster Truck tires offer heavy-duty support. Each tire measures 5 1/2 feet across, and a rough-and-tough vehicle such as Grave Digger needs every inch (all 66 of them) to keep on truckin’ across a track’s treacherous obstacles. Each massive Truck tire weighs in at over 800 pounds. This tire, called a terra tire, has deep treads that help the truck get a good grip, or gription, on the track’s dirt surface.
REPRODUCIBLE DATA DRIVEN
Objective: Students will use variations of the formula speed = distance/time (s=d/t) to Important Terms: calculate, organize, and present data gathered from a hypothetical Monster constant, distance, rate, Truck race. speed, time, variable Curriculum Connection: Exhibit Link: This lesson gives students an excellent opportunity to use and develop their mathematical problem-solving skills as they describe and measure Monster This lesson is designed as a Truck performance. Although no prior knowledge of speed as a scientific post-exhibit activity that property is necessary, experience with making/using tables, dividing whole will allow students to numbers by decimals, and solving multi-step problems is essential. connect their math skills to the Monster Truck driving Class Time: simulation and students’ sense of what it is like to 45-90 minutes roar toward the finish line. Materials Needed: pencils scratch paper reproducible calculators
Lesson Steps: 1. Write the letters MPH on the board. Many students will recognize this means “miles per hour.” Ask students where they see “miles per hour” outside the classroom and ask them for numbers of miles per hour with which they are familiar (such as 35, 55, and 65). 2. Using the number that seems most familiar to your students—e.g., 55—ask them what “55 miles per hour” means. Many will correctly say it means how fast you’re going; more/advanced older students will more specifically identify 55 miles per hour as a rate of speed. In any event, conclude this step with the fact that “miles per hour” is speed, and that speed is calculated using two measurements: distance and time. 3. Write s=d/t on the board. Refer to Step 2 and ask students what “s” stands for (speed). 4. Write the letters FPS on the board and ask students, if necessary, to compare this abbreviation with MPH to conclude FPS=feet per second. Ask students which of these two units of speed would be more appropriate for finding the time it takes to travel short distances, such as a walk from one end of your classroom to the other. Note: If your students are accustomed to using metric units, change the abbreviation to reflect the unit of measure of choice. 5. Introduce the student copy of the table below: 350-Feet Straight Track Race
Monster Truck Place Finish Time (seconds)+ Constant Speed (feet per second)* Grave Digger 1 6.262 55.893 Bulldozer 2 6.300 55.556 Monster Mutt 3 6.368 54.962 High Roller 4 6.377 54.885 Maximum Destruction 5 6.733 51.983 *rounded to the nearest thousandth + times are fictitious
GRADES 4-8 ★ UNIT 1 ★ MATHEMATICS • 9 The table represents data from a hypothetical Monster Truck race on a 350-ft. long straight-line track. Data missing from the students’ copy is in bold. 6. Guide students as necessary in a skim reading of the table. Students should note after this reading that the speed from the race is in feet per second. Briefly discuss why the trucks’ speeds are not in miles per hour—the units most often associated with automobiles. Use s=d/t to identify 350 feet as “d”, a distance appropriate for walking, but a distance a Monster Truck would travel in seconds—much faster than the students or any human could travel on foot. 7. Allow students to solve the problems on the student reproducible and to complete the table. Guide their work as necessary. Problems are sequenced in order of increasing difficulty. Answers are as follows: 1) 6.262 seconds 2) 55.556 ft per sec. 3) 6.368 sec 4) a = 6.733 sec; b = 51.983 ft per sec 5) range=0.471 seconds, which illustrates that there is less than a half-second difference between a first-place finish and a last-place finish; mean finish time=6.408 seconds; mean constant speed=54.656 ft. per sec. Please note that using the mean finish time as a way to figure out the mean constant speed will calculate to the answer: 54.619 ft. per sec — the discrepancy resulting from rounding. 6) 111.786 ft/sec 8. Conclude the lesson by checking the problems as a class and completing an overhead copy of the table. Use the range of the times to discuss how a little time—in this case, less than half a second—makes a lot of difference between a first-place or a “worst-place” finish.
Academic Extensions/Modifications: ELEMENTARY: Discuss with students the inverse relationship between time and place at the finish line: the less time it takes to finish, the greater your place. This concept, despite students’ playground experiences, sometimes seems counterintuitive to less experienced/younger students in a classroom context. MIDDLE SCHOOL: Provide more advanced students with a table minus all data and the data out of order of finish on the board or overhead. ETA @ Mile Marker (seconds) Use the table column at right as an extension of the table with 94.466 (1m 34s) which your students have been working. 95.039 (1m 35s) Instruct students to create a column for the ETA @ Mile Marker, 96.066 (1m 36s) and ask them how long it would take each truck to travel a mile, 96.201 (1m 36s) assuming speed is constant. Students must divide the number of feet in 1 mile (5,280) by the feet per second each truck is 101.572 (1m 42s) traveling. Students also can change the seconds into minutes and seconds by rounding each decimal to the nearest second and dividing it by 60 seconds using pencils and paper. These conversions also can be made by more advanced students mentally. This extension will again illustrate for students how close these times are—Monster Mutt’s and High Roller’s times, for example, are identical when rounded to the nearest second—and why speed during a race is measured to thousandths of a second.
10 • Mean Speeds Use the table to solve the problems below.
350-Feet Straight Track Race
Monster Truck Place Finish Time (seconds) Constant Speed (feet per second)* Grave Digger 1 55.893 Bulldozer 2 6.300 Monster Mutt 3 54.962 High Roller 4 6.377 54.885 Maximum Destruction 5 *rounded to the nearest thousandth
1. On a 350-ft. straight-line track, Grave Digger crosses the finish line .038 seconds before Bulldozer. If Bulldozer finished the race in 6.300 seconds, how many seconds did it take Grave Digger to win the race? Enter the data into the table.
2. Bulldozer finished the race in 6.300 seconds. Assuming Bulldozer’s speed was constant, what was the truck’s rate of speed? Enter the data into the table.
3. Given Monster Mutt’s constant speed on the track, how many seconds did it take the truck to cross the finish line? Enter the data into the table.
4. Not a good night for Maximum Destruction! This Monster Truck’s performance was monstrously unsatisfactory—Destruction crossed the finish line almost 4/10 of a second (0.356 seconds, to be exact) after High Roller. That’s not so slow, you say? Well, look at your completed table after you a) find Destruction’s finish time, b) find Destruction’s constant speed, and c) enter the data into the table.
5. Now that you’ve eyeballed all the trucks’ finish times and rates of speed, why do you suppose every thousandth of a second can matter in these short-distance races? Calculate the range of finish times and see what a difference a decimal can make. Also crunch your numbers to find the mean finish time and mean rate of speed.
6. Here’s a MONSTER challenge! In an actual race, the Monster Trucks would start from a standstill position and the initial speed would be zero. The constant speed you used to calculate times in your table is really a “mean speed,” also called “average speed.” If the average speed is defined as (initial speed + final speed) / 2, what is the final speed for Grave Digger?
REPRODUCIBLE FUEL FOR THOUGHT
Objective: Students will calculate amounts of fuel consumed or stored using fractions Important Terms: and decimals. capacity, consume, customary, dashboard, gauge, Curriculum Connection: metric This lesson is an excellent way for students to work with fractions and decimals as representations of the real-world energy source that moves Exhibit Link: Monster Trucks—and almost all of our automotive vehicles—every day: fuel. This lesson is designed as a Students should be able to multiply fractions and whole numbers and divide post-exhibit activity that decimals. will allow visitors to get a sense of how Monster Class Time: Trucks and all automotive 45 minutes vehicles consume fuel.
Materials Needed: pencils scratch paper fuel gauge reproducible calculators (optional) problem-solving reproducible
Lesson Steps: 1. As a class, discuss with students how one knows when it’s time to “fill it up,” or refill an automobile’s fuel tank. Students believing that they are pointing out the obvious might say, “When it’s empty”; you should point out that that’s too late. Sustain answers such as “almost empty” but ask students how much “almost empty” is. Point out, if necessary, that there’s something on an automobile’s dashboard that shows how much gas is “in the tank”—the fuel gauge. 2. Introduce the fuel gauge reproducible. Ask students what the markings represent and guide students as necessary to label the markings with the appropriate fractions. (For example, you could ask less advanced/younger students what the middle mark represents if the far right mark means “full.”) Tell them they should use a finger or pencil to represent the fuel gauge’s needle. 3. Using the fuel gauge, ask students again about when it’s time to refuel. If, for example, students say it’s when the needle drops below the 1/4 mark, ask them how much fuel they will need to fill up (1/4 full=3/4 empty). Guide this process as necessary, and ask how much fuel they’ll need when the tank is 1/2 and 3/4 full. 4. If students have not already discussed these amounts as gallons, introduce the term. In any event, you likely will need to remind students that a) gallons are units of capacity; and b) capacity is a measure of how much a container, such as a fuel tank, can hold. 5. Ask students whether they know how many gallons of fuel an automobile can hold. This is an excellent opportunity to further engage students’ prior knowledge and inference skills. Students might recall how many gallons of gas it takes to fill up the family automobile and conclude through discussion and/or prior observation that different vehicles have different fuel capacities. Guide students to this conclusion as necessary. 6. Introduce to students the fuel capacities of three familiar vehicles: the five-seat Toyota Tercel (11.9 gallons); a Ford Sport Utility Vehicle, the Explorer (22.5 gallons); and Grave Digger (20 gallons). 7. Ask students to estimate how much fuel each vehicle contains when it’s 1/2 full. Either independently or as part of guided practice, students should multiply each of the three fuel capacities above by 1/2 to determine the number of gallons of fuel in a 1/2 full tank, which students should infer will also be the
12 • GRADES 4-8 ★ UNIT 1 ★ MATHEMATICS number of gallons that have been consumed (Tercel=5.95 gallons; Explorer=11.25 gallons; Grave Digger=10 gallons). 8. For each of the vehicles, ask students to find the number of gallons of fuel 1/4 full and 3/4 full represents. The answers are below, along with the number of gallons each vehicle contains when it is 1/4 empty and 3/4 empty: Vehicle Total Fuel Capacity 1/4 full 3/4 empty 3/4 full 1/4 empty
Toyota Tercel 11.9 gal. 2.975 gal. 2.975 gal. 8.925 gal. 8.925 gal. Ford Explorer 22.5 gal. 5.625 gal. 5.625 gal. 16.875 gal. 16.875 gal. Grave Digger 20 gal. 5 gal. 5 gal. 15 gal. 15 gal.
9. Conclude the lesson by introducing the problem-solving reproducible to be completed in class or as homework. Students will need their answers to Step 7 to complete the problems. Problems are sequenced in order of increasing difficulty. Answers are as follows: 1) 20 miles; 2) 2.5 or 2 1/2 gallons; 3) 12.5 or 12 1/2 full, 7.5 or 7 1/2 gallons empty; 4) 16 gallons, 4 gallons; 5) #2 = 9.48 liters, #3 = 47.36 liters full and 28.43 liters empty, #4 = 60.64 liters and 15.16 liters.
Academic Extensions/Modifications: ELEMENTARY: For less advanced/younger students, Step 5 is an excellent opportunity to reinforce the concept that proportionality is relative, and that the value of a fraction of a whole number changes, or varies, when the whole number’s value changes, or is variable. For example, you can guide students to the discovery that 1/2 the fuel capacity of the Explorer is about the same as the fuel capacity of the Tercel, which stands to reason because the Explorer’s total fuel capacity is about twice the Tercel’s total fuel capacity. Cut out and laminate a photocopy of the fuel gauge, station it with dry erase markers, and allow students during free time to correctly match fractions to their locations on the gauge; then, calculate the fraction of fuel stored or consumed based on a randomly drawn number indicating the capacity of the fuel tank.
MIDDLE SCHOOL: In Step 7, more advanced/older students likely will see that they can save a step by dividing the fuel capacities by 2, instead of first multiplying by 1/2; ask them whether the multiplication step can be skipped when the numerator is greater than 1, as in 3/4. As they will see in subsequent problems, multiplication sometimes will be necessary. The table in Step 8 includes the “quarters-empty” amounts to help you illustrate for students, if necessary, that there is more than one way to solve these problems. In the event you wish to reproduce the table above (either with or without the answers), you can use it to help students realize that the “quarters-empty” amount can be calculated by subtracting the “quarters-full” amount from the total fuel capacity.
• 13 FUEL FOR THOUGHT
Solve each problem. Read carefully. All fractions should be represented in simplest form.
1. Assume that for every gallon of fuel that Grave Digger consumes, the truck can run for 2 miles. If Grave Digger’s 20-gallon tank is 1/2 full, how many miles can Grave Digger go before needing to be refueled? ______
2. Only 1/2 of Grave Digger’s 20-gallon fuel tank remains full. Unfortunately, 1/4 of that remaining fuel has leaked. How much fuel has leaked from Grave Digger’s tank? Write your answer as a decimal and a fraction. ______
3. After a busy day, 5/8 of Grave Digger’s 20-gallon tank remains full. How many gallons of fuel are left in the tank? How many gallons have been consumed? Write your answers as decimals and fractions. ______
4. Grave Digger’s 20-gallon fuel tank is 80% full. How many gallons of fuel are in the tank? How many more gallons can be filled? ______
5. Look back at your answers for problems 2-4. If 1 gallon = 3.79 liters, how many liters do each of your answers equal? Round your answers to two decimal places. ______
6. Be the teacher! Create a problem of your own using concepts from this lesson. State the problem clearly and challenge a classmate to solve your problem. If your classmate cannot solve the problem, explain the problem to your classmate. Share your problem with your teacher and explain how you decided on the type of problem to create.
REPRODUCIBLE MEASURES OF GREATNESS
Objective: Students will use the concepts related to kinematics to acceleration, Important Terms: measure and calculate the time, distance, speed, and distance, kinematics, speed, velocity acceleration of toy cars. Advanced students will graph distance versus time to determine speed, and speed versus time to Exhibit Link: determine acceleration. This lesson serves an excellent pre- Curriculum Connection: exhibit activity. Monster Trucks require The beginning of physics is rooted in describing motion incredible power to accelerate and move (kinematics). To describe motion, we begin by measuring through obstacle courses at amazing distance and time. From distance and time measurements, we speeds. It will be helpful for students to can calculate speed and acceleration. Speed can be calculated by understand how the concepts of speed, dividing the distance traveled by the time (s = d/t). If the speed distance, and acceleration relate to trucks is measured at two different times (e.g., 15 ft/s and then 20 ft/s prior to seeing them in action. When two seconds later), the acceleration can be computed by dividing students visit the Safety Seats area of the the difference in speeds (20 ft/s - 15 ft/s) by the time between the exhibit, they can then experience a sense measurements (5 ft/s/2s = 2.5 ft/sec2). For the purposes of this of acceleration, deceleration, and going lesson, linear motion is used (with no changes in direction); up/down an incline. therefore speed = velocity, and distance = displacement.
Class Time: One 50-minute class period is required to measure the speed, and one 50-minute class period is required to measure the acceleration. Additional time may be required to produce the graphs.
Materials Needed: graph paper pencils, pens incline planes (wide, long boards) stopwatches (or watch with a second hand) wind-up cars (or battery operated cars) measuring tools: rulers, meter sticks, yard sticks or tape measure
Lesson Steps: 1. As a class, spend 10 minutes introducing or reviewing the terms above related to kinematics. Modify the level of detail of the concepts based on your classroom skill level. An important point to consider for this lesson is that for linear motion, speed and velocity are interchangeable. If the lesson involved a change in the direction of the cars, then the more complicated concepts of velocity as a vector and displacement would need to be introduced. These concepts are generally too advanced for grades 4-8. 2. Provide pairs of students with electric/wind-up cars (that travel at a constant speed), rulers, and clocks. If stopwatches are not available, the activity can be completed in a gym that permits extension of the distance (and time) so that a clock with a second hand sweep can be used and still provide reasonable measurements. Note: Before beginning this activity, “test drive” the cars to ensure that they go at a constant speed and in a straight line for a distance of about 2 meters. 3. Instruct students to map out a course (beginning and ending points), measure the distance between the points, and record the time it takes their cars to complete the course. All information should be recorded in chart format. 4. Using the formula of speed = distance/time, students should calculate the speed of their cars. Measurements can be expressed as fractions and then converted to decimals.
GRADES 4-8 ★ UNIT 1 ★ SCIENCE • 15 5. Based on their calculated speeds, ask students to predict who will win an actual race between the cars. Students can then confirm their predictions by head-to-head competitions on the course. 6. If time and space permit, students may alter the course and repeat Steps 3-5 to see if the results change. 7. Upper level classes should now proceed on to measurements of acceleration. For accelerated motion, the same cars should be used but measured while moving along an inclined plane set up on the course. Add a long, inclined plane (wide board raised at one end) at the beginning or end of the course. The length of the course that runs on level ground need not be the same as that used in Step 3. 8. Students first race their cars up the ramp to demonstrate negative acceleration. Instruct students to record the time it takes just to get up the ramp from its beginning (=t). After running the cars on a level surface (but before beginning up the ramp), the cars will have an initial speed as measured in step 4 (=vi). As the cars move up the ramp, they will slow and eventually stop. (If the car does not come to a stop by the end of the board, simply increase the angle of the ramp until the car does stop at the end. You may wish to determine the required angle of the ramp prior to class.) The final speed (=vf) will then equal zero. 9. Students should use the following equation to determine their car’s average acceleration (this value will be negative in sign): a = (vf -vi)/t
10. Students will then race their cars down the ramp to demonstrate positive acceleration. The time it takes to go down the ramp alone should be measured (=t). Since the cars begin to move from a standstill, the initial speed (=vi) is zero. To find the final speed (=vf), Step 3 should be repeated after the car has left the ramp. (It is best if the course used here is rather short.) 11. Students then use the same equation to determine their car’s average acceleration: a = (vf -vi)/t
This value will be positive in sign.
12. To observe the effects of the angle of the ramp on acceleration, the cars can be raced up the ramp as in Step 8. The distance of the point at which the car stops should be measured from the beginning of the ramp. Have students then measure the angle of the ramp with a protractor. The angle of the ramp can be increased and the new stopping distance measured. Students then summarize the data in a table that shows the angle of the ramp (at several settings) versus the stopping distance. Students should note that as the angle increases, the stopping distance decreases.
16 • Academic Extensions/Modifications: ELEMENTARY: In grades 4-6, it is appropriate for students to complete Steps 1-6 to simply measure time and distance and compute speed as a fraction or ratio (e.g., 15ft/2seconds.) Students can also be given a compass to measure direction (i.e., “due north”). Although the direction information is not used in these calculations, it provides a basis for later explorations that require direction information (to compute vector quantities such as velocity and acceleration) and serves to reinforce geography concepts. The measurement of distances also provides an opportunity to discuss scales (English v. metric), conversion (from one scale to another), and units (and how they are expressed). MIDDLE SCHOOL: In grades 7-8, as an extension for exceptionally gifted classes, students can plot distance versus time. (The slope gives you speed.) Students should also graph speed versus time, and measure the change in slope of the speed graphs to compute acceleration. If the acceleration is graphed against time, the graphs are linear. The important point to be noted is that in some cases (cars on a flat surface), a distance-time graph renders a linear function with a slope equal to the speed. In other cases (cars on a ramp), the same graph is non-linear, indicating a variable speed (accelerated motion). Further, a positively curved function shows an increase in speed (down the ramp) while a negatively curved function shows a decrease in speed (up the ramp).
Writing Prompts/Potential Discussion Questions: 1. While the car is moving on a flat surface, its speed is constant. If it moves 5 ft in 2 seconds, how far will it move in the next 2 seconds? In the next second after that? 2. While the car is moving down the ramp, its speed increases. What causes this increase in speed? 3. If a car is simply rolled down a ramp, it will eventually stop when it moves onto a level surface. Why? 4. When the car is moving up the ramp, it slows down. What causes it to slow down? 5. In high school physics, you will learn that speed is a scalar and velocity is a vector. Use the dictionary, or other sources, to explain the difference between a scalar and a vector. Give three examples of scalar quantities and three examples of vector quantities.
• 17 BRAIN BUCKET
Objectives: To reinforce the concepts of force and motion as they Exhibit Link: relate to Monster Truck safety, students will design an “egg carrier” to protect an egg when dropped. Students This lesson works well as a pre- or post-exhibit will test the usefulness of their design by dropping the egg activity. Given Monster Truck’s concern for carrier from different heights and identifying the design safety, drivers wear a lot of protective gear, the features most useful in protecting the egg. Students will most important of which is a helmet, or “brain relate this information back to the design of safety helmets, bucket.” Issues related to helmet integrity and its or “brain buckets,” worn by drivers. ability to protect a driver’s head will be explored in this “egg drop” exercise. After realizing the Curriculum Connection: importance of helmets in the pre-activity, This lesson serves as an excellent review of the scientific students visiting the exhibit will look closely at concepts of force, motion, and acceleration. The activity head protection in the Safety Seats video. The enables students to put scientific principles into practice and Strap-In simulation also reinforces the need to explore the subject of technological design. protect your head. As a post-activity, students can make notes regarding the materials and Class Time: designs used for driver helmets, and apply that knowledge to their own “brain bucket” designs. One-to-two 50-minute class period(s) to plan and make the egg carriers, and one 50-minute class period to test egg carriers.
Materials Needed: raw eggs cotton batting tape string glue small boxes Styrofoam peanuts packing materials plastic straws cleaning materials to wipe up eggs when they break plastic sheet for egg testing area
Lesson Steps: 1. In this lesson, students will use an egg drop exercise to simulate the forces of motion exerted on the human head during a Monster Truck crash. It may be helpful to review the concepts of force and motion and how they affect objects during a crash prior to completing the lesson. 2. Divide students into pairs or teams and provide each with a raw egg and a constant set of materials (e.g., cotton batting, tape, small boxes, string, cloth, padding, etc). Inform students that their task is to use the materials provided to build a cocoon designed to protect their egg. Students should consider the design elements (size, shape, weight) of existing protective gear and take them into consideration for their “brain buckets.” Provide 1-2 class periods for students to design, construct, and pre-test their “brain buckets.” (More than one raw egg per team may be needed if testing is allowed.) 3. Arrange for students to have safe access to drop their buckets from progressively taller heights. The eggs should be examined after each drop to ensure integrity. Dropping the eggs from increasing heights will test designs. The design that protects the egg best from the greatest height wins. You may wish to videotape the egg drops for analysis during the activity conclusion. 4. As a conclusion, ask students to analyze and discuss the design features that led to success or failure.
18 • GRADES 4-8 ★ UNIT 1 ★ SCIENCE Academic Extensions/Modifications: ELEMENTARY: If time and materials permit, students can also be encouraged to add an artistic element to their “brain buckets.” MIDDLE SCHOOL: For grades 7-8 or advanced classes, the same activity can be completed with the modification that students are free to use whatever materials they desire. Students can be encouraged to research materials they believe are best to use, and arrive at unique designs. As pairs of students lock into and “patent” a design, other teams are prevented from using it. This results in a larger number of designs for analysis of factors that result in success or failure. This exercise can be extended by taking successful design features (e.g., wrapping the egg in cotton) and systematically varying the feature (increasing the amount of cotton), while keeping other features constant. Subsequently, students can determine if the design feature actually provides additional protection. For advanced classes, the increase in height from which eggs are successfully dropped can be compared across design features to rank order their utility. For example, have some students double the amount of cotton used in their successful design, while other students double the amount of Styrofoam peanuts. If the eggs in the cotton can now survive a fall from twice as high, but the eggs in Styrofoam can now only survive a drop from 50% higher, it can be concluded that the cotton is more effective as a safety design than Styrofoam.
Writing Prompt/Potential Discussion Question: After students have identified several features that help protect the eggs, ask them to identify those that might be most useful in designing a helmet for a Monster Truck driver. What additional factors must they consider when designing a helmet?
• 19 A MATTER OF MOMENTUM
Objective: In this inquiry-based learning activity, students will observe cars displacement, Important Terms: (or balls) undergoing a collision and calculate the momenta of the kinematics, Law of Conservation of cars/balls before and after the collision. Students will conclude that Momentum, momentum, momenta, the total momenta before and after a collision is the same, thus velocity, speed observing the Law of Conservation of Momentum. As an extension, students can alter the weight of the cars/balls and observe the effect Exhibit Link: on the momentum of each after a collision. The exhibit’s Safety Lab looks Curriculum Connection: closely at the precautions necessary A fundamental principle in physics is the Law of Conservation of when collisions (and the momenta Momentum. The momentum of an object is defined as the product of associated with them) occur at its mass and velocity. If two objects have the same mass and velocity, Monster Truck meets. This lesson their momenta are equal. If friction is ignored and the objects collide can be presented before or after head-on, they will both rebound in opposite directions but with the visiting the exhibit. same speed. However, if one object has a greater momentum (because of a heavier mass and/or a greater velocity), both will move off in the direction of the object with greater momentum but with a smaller speed. The total momenta of the objects before and after the collision will be the same.
Class Time: One 50-minute class period for teacher guided discussion and small group facilitated learning on how to measure the momentum. Additionally, one 50-minute class period is needed to measure the momentum of cars undergoing different types of collisions.
Materials Needed: rulers balance washers tape Hot Wheels® track long, wide boards for ramps stop watches (or watch with a second hand) small rubber balls to tape on the cars non-motorized cars (matchbox) of varying weights, or balls of similar and varying weights chart for recording data (teachers may wish to create their own chart handouts for this activity)
Note: You may wish to substitute balls in place of cars. You will need to provide balls of differing weights for students to choose from and use for the extension activity. If you choose to use balls instead of cars, be sure that the balls fit inside the Hot Wheels® track adequately.
Lesson Steps: 1. After introducing or reviewing the concepts of kinematics, provide students or teams with matchbox cars, rulers, clocks, small rubber balls, tape, and boards. If stopwatches are not available, the activity can be completed in a gym that permits extension of the distance (and time) so that a clock with a second hand sweep can be used and still provide reasonable measurements. If cars are used, instruct students to firmly tape the small rubber ball to the center of the front bumper of their car, making sure the ball does not touch the floor. 2. Instruct students to map out a course (beginning and ending points) with the Hot Wheels® track, and measure the distance between the points (about 4 feet is plenty). The board ramp should be set up at the edge of the beginning of the course (lay additional track on the board lined up with the course track) so that when released, the car will roll down the ramp and onto the beginning of the course.
20 • GRADES 4-8 ★ UNIT 1 ★ SCIENCE 3. Students should record the time it takes for their car/ball to roll from the beginning to the end of the course. All information should be recorded in chart format. Note: Students should start their stopwatches when the cars hit the beginning point of the course; time going down the ramp should NOT be included. 4. Using the formula of speed = distance/time, students should calculate the speed of their cars. Measurements can be expressed as fractions and then converted to decimals. 5. After students have measured the velocity (speed in one direction) of their vehicles, they must weigh each car (with the ball attached.) Using the balance, students should weigh and record the weight of each car. (Although mass is technically required to compute momentum, weight is a mathematically equivalent value.) Based on the measurements, students should pair up cars that have both the same or nearly similar weights and the same or nearly similar velocities. 6. Next, students should compute and record the momentum of each car in their pair using the formula: momentum = mass x velocity Note: Students will need to convert units used for mass and velocity to metric units.
7. Set up an equal pair of board ramps, one at each end of the previously measured track course. Starting at the opposite ends of the ramps, students should set up a head-to-head collision between their two cars/balls of equal or very similar weights and velocities. When the cars/balls run into each other, they rebound in opposite directions with the same speeds. Students should note that the cars rebound all the way back to their respective ramps. 8. Have students repeat Step 7 in order to measure the speeds of the cars/balls after they have collided. Since the length of the course is already known, it can be divided by 2 to find the distance each travels after the collision. Students then record the time starting with when the cars/balls collide to when they stop moving backwards. Using their data, students then calculate the speed (velocity) of the cars/balls after collision. 9. To observe the Law of Conservation of Momentum in action, students use the formula again to calculate the momentum of each car/ball after collision. Compared to their calculations from Step 6, no change will be noted if the cars/balls are equally matched for velocity and weight. Ask students to explain why this happens. (Answer: Following the law, the total momenta of both cars/balls before and after the collision are the same.) 10. Distribute the reproducible to complete in class or as homework. Answers: 1.a) momentum = 125,500; b) momentum = 60,250; c) Blue Thunder; 2) approx 35 mph; yes. 3) Radical Rescue would win. You would have to add 1029 lbs to Blue Thunder before it would win.
Academic Extensions/Modifications: ELEMENTARY: This lesson can serve as an excellent inquiry-based learning activity for younger students to help them understand the concept of momentum. You may wish to create a large chart on the board that the class fills out as a whole after performing the experiment together. Depending on their skill levels, you may also wish to guide students through the formula calculations using the data that they collect.
• 21 MIDDLE SCHOOL: Reminding students of the formula for calculating momentum, ask them to predict what might happen to their cars/balls in a collision when one of the cars is heavier than the other. (If the cars/balls have similar velocities but quite different weights, both cars/balls will travel in the direction of the heavier car.) To observe this, instruct students to alter the weight of one of their cars by taping washers to it. Students should then repeat Steps 7 - 9 and observe what happens. (Balls of differing weights but similar velocities can also be used in place of the cars.) Note: When they are calculating momentum, remind students that momentum is a vector quantity, meaning that the direction of travel matters. Consequently, travel in one direction can be taken as having a positive velocity (and momentum), while travel in the opposite direction is assumed to have a negative velocity and momentum. For students in higher grades, you can extend this activity to a more advanced experiment in which cars with quite different speeds but similar weights collide with each other. The cars will both move off in the direction of the faster car. Students can measure the momentum of each car, before and after the collision, and confirm that there is no change in the total momenta of both cars together before and after the collision. If a light car collides with a heavier one, it will lose the contest. However, if the weight of the lighter car is increased, so is its momentum. At some point, it will have a momentum equal to the heavier car and the cars will rebound in opposite directions. If the weight is further increased, it will “win” in the collision contest. Students can be asked to predict how much weight must be added for their car to win. These predictions can be confirmed in a collision contest.
Writing Prompts/Potential Discussion Questions: 1. When cars collide, their momenta change. But what remains constant? 2. Sometimes when the cars collide, they rebound in opposite directions. Which car has the greater momentum? 3. Sometimes when the cars collide, they both move off in the same direction. Which car has the greater momentum? What happens to its speed? 4. If play dough is put on each car’s front bumper, they will stick together. What do you think happens to their momenta? This is an example of a “sticky” collision, called an “inelastic” collision. The momenta before the collision is zero because the two objects have the same mass but opposite velocities. After the collision, the total momenta MUST be zero, which happens in this case because both objects come to rest (if perfectly inelastic) and mass times zero is still zero. A good example of this is from football when two large linemen of roughly equal mass and opposite velocities collide head-on. Neither lineman moves very much! The same thing would happen with Monster Trucks.
22 • Monster Momentum!
Now it’s time to see what might happen if you match up Monster Trucks and normal cars in a head-to-head momentum battle! Using the information below and the formulas you have learned for calculating velocity and momentum, solve the following hypothetical problems.
Vehicle Weight Maximum Velocity Blue Thunder 10,400 lbs 70 mph Radical Rescue 10,000 lbs Over 80 mph Honda Accord 2,994 lbs Over 120 mph
1. a. If Blue Thunder is moving at 60 mph, what is its momentum?
b. If an Accord is moving at 100 mph, what is its momentum?
c. If they have a head-on collision, who will win? Why?
2. If Blue Thunder is moving at 10 mph, how fast would the Honda have to move to win a head-to-head collision? Can the Honda go that fast?
3. If Radical Rescue is moving at 80 mph and collides with Blue Thunder moving at 70 mph, who would win?
How much weight would you have to add to the losing truck before it would win?
REPRODUCIBLE 24 •
MONSTER-SIZED MECHANICS
Objectives: acceleration, Students will learn to measure the acceleration of vehicles Important Terms: undergoing constant acceleration and will practice graphing the coefficient of friction, net force, results. Students will then use the mass of the vehicle and its projectile motion acceleration to compute the net force. Students will complete a force diagram for a Monster Truck and compute the motive force of Exhibit Link: a Monster Truck engine. Finally, given the angle of an incline (off of This lesson can be completed either which a Monster Truck jumps) and the initial velocity, students will as a pre-or post-exhibit activity. The compute the height and length of the jump. exhibit’s computer simulation of Curriculum Connection: driving a Monster Truck will give a sense of acceleration, deceleration, These activities provide an excellent way to introduce students to and what it’s like to “catch some air.” measurements of acceleration, graphical analysis of motion, Newton’s This lesson helps students understand Second Law of Motion, force diagrams, and the analysis of projectile the physics behind these motions. motion. Although students may have covered this material in a lecture, hands-on activities make the abstract physics concrete.
Kinematics and dynamics are covered first in most physics curricula. Kinematics involves a description of motion (velocity, acceleration, etc.) while dynamics entails the causes of motion (forces). The combination of kinematics and dynamics is known as mechanics. This lesson uses paper and pencil as well as lab activities in order to provide students with a better understanding of the mechanics of motion.
Since Monster Trucks have an initial velocity of zero (and accelerate to some maximum velocity), students will measure different acceleration curves as a pre-activity in class. Although these labs explore constant acceleration curves, realistic vehicles, having a gas pedal and a transmission, exhibit non-linear acceleration curves. Several assumptions can be made, depending on the ability level of students. For a regular level class, students can assume a constant acceleration and compute it from the initial and final truck velocities. More advanced classes can contemplate a step function as drivers shift gears. AP/IB classes (which often take a calculus approach) can use “real” acceleration curves and compute derivatives.
Once students determine the acceleration, they can compute the net force acting on the Monster Truck using the formula (Fnet=ma). Depending on which of the above assumptions is used, the corresponding net force can be derived (constant force, step function, or derivatives). Given knowledge of the coefficient of friction between the wheels and the road and the mass of the truck, the motive force of the engine can be computed after constructing a force diagram. It’s awesome!
The final part of the lesson examines one of the more exciting things about Monster Trucks—when they “catch some air.” This is a study of projectile motion. Such motion is best analyzed by resolving the velocity into a vertical component (a function of gravity which varies) and a horizontal component (which is constant) gained from the Monster Truck while still on the ground. The distance it travels as well as the height it jumps are a function of the initial velocities before take-off and the angle of the ramp used. Students will set up ramps and use wind-up cars to simulate the effect.
Class Time: Acceleration Pre-activity: one 50-minute class period to measure, 1/2 period to graph Force Analysis: 50 minutes Projectile Motion: 50 minutes
26 • GRADES 9-12 ★ UNIT 2 ★ PHYSICS Materials Needed: carts protractors wind-up or battery-operated cars rulers graph paper ticker-tape timers (or stopwatches) incline planes (the longer the better; wide boards are good)
Lesson Steps: This lesson contains three parts: measuring acceleration, completing a force analysis, and analyzing projectile motion.
Part 1: Measuring Acceleration 1. Instruct students or student teams to place a cart on the top of an inclined plane (an angle between 20°- 40° is best) and connect the ticker-tape timer to it. After activating the timer, they should let the cart roll down the incline. 2. After the cart stops, students should measure the distance between “ticks” on the ticker tape. These measurements should then be organized in tabular format showing the cumulative distance between ticks and the time interval. The time interval to each tick equals the number of ticks (attained by counting ticks) times the length of time between a pair of ticks. That value is typically 1/60 of a second but may vary across timers. 3. Using the graph paper, have students graph these cumulative distances against the time interval. This graph will show positive acceleration (i.e., the graph will be non-linear with an increasing slope). 4. Using their graphs, students should: • estimate the slope of this graph at several points (the slope is an estimate of the speed at that point in time) • graph these speeds against the time at which each was taken. 5. Using their graph of speed against time, students then compute the slope of the curve, which is the acceleration of the cart.
Part 2: Force Analysis 1. Using the same materials as Part 1, students should measure the mass of the cart using a balance. 2. Then, using a protractor, students should measure the angle (q) of the incline set up in Part 1. 3. Given the mass and the acceleration (value derived in Part 1), instruct students to compute the following equations for force acting on the cart:
a) net force (Fnet = m·a) 2 b) gravitational force (Fg = m·g, where g = 9.81 m/s ) c) normal force (N = m·g·cosq, where q = angle of the incline) d) friction force (f = uk · N, where uk = the co-efficient of friction. A value of 1.0 is reasonable for this lesson.) 4. Guide students in using vector addition to add the gravitational force, the normal force, and friction force. The sum should equal the net force. 5. Now, to compare these forces on a larger scale, supply students with the following data: Truck Mass Constant Speed Blue Thunder 10,400 lbs 70 mph Given the acceleration and mass of Blue Thunder traveling on a level surface (q= 0), students should repeat Step 3 and record their calculations for forces acting on the trucks. (Students must first convert the lbs and mph to metric values.) Note: Be sure to point out that since the truck is moving at a constant velocity, its acceleration is zero.
• 27 6. Guide students in finding the sum of the gravitational, normal, and friction forces in Step 5 using vector addition. 7. Lead students to observe that the sum of those forces does not equal the net force calculated in Step 5. Ask students why they think that is so. (Answer: The motive force supplied by a Monster Truck engine has not been accounted for yet.) 8. Instruct students to create a Free Body Diagram of the Monster Truck. If the net force and friction force are known, ask students how they can determine the fengine . (The answer is explained in Step 9.) 9. Guide students in using vector subtraction to find the difference between the net force and the other forces calculated in Step 5. 10. Ask students to observe that the difference in forces in Step 9 equals the motive force of a Monster Truck.
Part 3: Analyzing Projectile Motion In this section, students will use the initial velocity [v] of a Monster Truck and the angle [q] of the jump ramp (a typical value is 20°), to compute the horizontal [vx = v·cosq] and vertical [vy = v·sinq] components of velocity in a Monster Truck jump.
1. Lead students to observe that the vertical component determines the height of the jump [dy = (vyt) – 2 2 (gt /2)] as well as how long [t = vy/g, g = 9.81 m/s ] the Truck is in the air. Further, students will note that this time and the horizontal component can be used to compute the length [dx = vxt] of the jump. 2. Students should use the velocity values they compute (vx and vy) and the equations from Step 1 to compute the height and length of a typical Monster Truck jump. 3. If time permits, these predictions can be tested by setting up ramps (at various angles), running cars up them, and measuring the height and distance of the jumps. If the initial velocity and angle are known, the length of the jump can be predicted and compared with the measurements.
28 • 4. Student teams can use the following steps to test these predictions. This experiment works best with fast moving cars, short take off ramps, and small angles of incline: a) Map out a course and measure the distance from beginning to end. b) Run the battery-operated car along this course and measure the time it takes to complete the course with a stopwatch. Compute the velocity using velocity = distance/time. c) Set up a ramp and measure the angle of the incline. d) Repeat Steps 1 and 2 above but use the velocity of the car and the angle of the ramp to predict the length and height of a jump. e) Direct the car to run up the ramp. f) Note where the car lands after running off the ramp. g) Measure the distance from the end of the ramp to where the car lands. This “jump distance” can be compared with the mathematical predictions. h) Place a ruler in a vertical orientation about mid-way between the end of the ramp and where the car lands. Estimate the height of the jump and compare it to the “height distance” prediction.
Academic Extension/Modification: The above activities assume a constant acceleration. Real vehicles shift gears and have variable acceleration curves. If acceleration values for each gear in a typical car can be obtained (and are approximately constant in a gear), the velocity-time graph has several discontinuities at which the slope (and therefore acceleration) changes. The number of discontinuities equals the number of gearshifts. This more realistic data permits computation of the net force as a step function. Further, for Physics classes taking a calculus approach, real acceleration curves (that are non-linear) can be analyzed using derivatives.
Writing Prompts/Potential Discussion Questions: 1. Upon inspection, the ticks on the ticker-tape time become increasingly spread out. What does this indicate about the velocity?
2. Upon more careful inspection, the space between successive pairs of ticks on the ticker-tape timer increases, but by a constant amount. What does this indicate about the acceleration? About the net force?
3. As a cart rolls down an incline, it accelerates. What force is the cause of this acceleration?
4. As a Monster Truck shifts gears, its acceleration increases in a non-linear manner. What does this indicate about the Truck’s acceleration? What does that indicate about the net force? What is the source of the force responsible for the acceleration?
5. When computing the distance a Truck travels when it jumps off of a ramp, you should compute the height of the jump first. Why?
• 29 ENERGY: IT HAS TO GO SOMEWHERE
Objectives: Law of Students will identify sources of friction in a Monster Truck Important Terms: (engine, drive train components, road surface, and wind Conservation of Energy, kinetic energy, resistance) and the energy content (potential energy) of methanol potential energy, work from the Handbook of Chemistry and Physics. Using those values, students will compute the work done by a Monster Truck engine. Exhibit Link: Students will also compute the amount of energy lost to friction and This lesson is best used as a post- heat losses. Finally, students will compute the efficiency of a exhibit activity. The Monster Truck Monster Truck. drive train section of the exhibit will Curriculum Connection: provide a valuable way for students to experience and discover the inner The Law of Conservation of Energy holds that the total energy workings of a Monster Truck—the before and after an event remains the same. This provides a much same inner workings that are at the easier way to measure friction, a major concern in any machine. heart of this lesson.
In a Monster Truck engine, chemical potential energy in methanol gets converted into the mechanical energy of pistons, then into rotational energy of the drive train, then into rotational energy of the wheels, and finally into kinetic energy of the Truck (less friction of the tires with the road, wind resistance, friction in drive train components, and the energy lost in tailpipe emissions). Students will first calculate the energy content of a gallon of methanol, which is the initial potential energy. They will then calculate the work done by a Monster Truck engine. If these values differ, the loss is due to friction and energy lost via tailpipe emissions. The ratio between the work and the energy content of methanol leads to an efficiency computation (= work/energy of the methanol).
Note: Students will need to have a working knowledge of reciprocating engines and drive train components to identify how the engine works and where friction arises. You can use the reproducible to review energy transfers and losses to facilitate their understanding.
Class Time: 50 minutes
Materials Needed: None
Lesson Steps: 1. Using the following values, have students calculate the mileage of a Monster Truck (miles/gallon of methanol). This can be computed by dividing the typical number of miles a Monster Truck travels on a tank of fuel (d = 3 miles) by the number of gallons the fuel tank holds (g = 20 gallons of methanol). 2. Students should convert the mileage expressed as miles/gallon to meters/mole of methanol. The distance in miles can be converted to meters by the following conversion: distance in meters = distance in miles x 1610. The number of gallons of methanol can be converted to moles of methanol by the following conversion: methanol in moles = methanol in gallons x 93.47. 3. Prompt students to find the heat of combustion for a mole of methanol (∆Hc = -726.34 kJ/mole), then have them compute the chemical potential energy in a tank of Monster Truck fuel [PE = (∆Hc)x (number of moles of methanol in the fuel tank)].
30 • GRADES 9-12 ★ UNIT 2 ★ PHYSICS 4. Given the distance a Monster Truck can travel on a tank of fuel (=d, in Step 1) and the motive force of a Monster Truck engine (approx 45,000N), students will calculate the work done by a tank of fuel (W = Fengine x d). 5. Ask a student to state the Law of the Conservation of Energy. Then have students compare the PE and work they computed for a Monster Truck. Since these values will differ (less work), ask students to explain why that might be. (Answer: energy losses due to friction, wind resistance, etc.) 6. As a conclusion, have students calculate the efficiency of a Monster Truck engine using the formula (efficiency = Work/PE). This number will be less than 1.0. Usually, efficiency is expressed in percent. To convert the ratio Work/PE to percent, multiply by 100.
Academic Extension/Modification: Students can explore the effects of lubrication on the friction losses in the engine and drive chain components. Alternately, students can explore changes in a Monster Truck shape that might improve wind-resistance.
Writing Prompts/Potential Discussion Questions: 1. Methanol molecules store chemical potential energy in chemical bonds. Given knowledge of chemistry, how is this energy stored? 2. Typically, combustion of any fuel is incomplete and leads to pollution. This also reduces the potential energy available to make a vehicle move. How can testing tailpipe emissions be used to better compute the available potential energy? 3. Monster Trucks are more efficient than passenger cars. What variables make this possible?
• 31 Energy Transfers and Losses
Energy Transfers
Energy released Oscillatory Rotation of Rotation of Forward during motion of drive axle and motion combustion a piston shaft tire of Monster Truck
Energy lost Friction Friction in Friction with Wind as heat in with a variety road resistance exhaust gasses cylinder of drive train surface components Energy Losses
REPRODUCIBLE TONS O’ TORQUE
Objective: angular Students will calculate the moments of inertia and average angular Important Terms: accelerations of a Monster Truck drive shaft and tire in order to acceleration, angular momentum, compute the torque acting on each. As an extension, students can angular velocity, moment of inertia, compute the forward speed of a Monster Truck given the RPM of a torque Monster Truck terra tire and its radius. Exhibit Link: Curriculum Connection: This lesson is best covered after This lesson provides an excellent supplemental activity to a physics of visiting the exhibit, as it requires a rotation focus. The lesson enables students to explore the concept of working knowledge of engine and torque, particularly as it applies to Monster Trucks. After some quick drive train components. The exhibit demonstrations of torque outside of an automotive context, students Shop area includes a Monster Truck will arrive at a working definition of the term, understanding that it Drive Train for visitors to can result in the rotation of an object. From there, students will experience and discover the inner explore how several theoretical physics concepts are applied to real workings of a Monster Truck. systems (such as Monster Trucks).
Class Time: 50 minutes
Materials Needed: socket wrench nut/bolt (a seesaw, triple beam balance, or screw drivers where the diameter of the handles vary can be substituted)
Lesson Steps: This lesson is comprised of three parts. Part 1 is a demonstration of torque. Part 2 calculates the torque acting on a Monster Truck drive shaft. Part 3 calculates the torque acting on a Monster Truck tire.
Part 1: The concept of torque can be demonstrated in any number of ways. One convenient way involves a socket wrench. To demonstrate the concept of torque to your class:
1. Present a nut tightened on a bolt to each student in your class. 2. Allow each student to use the socket wrench to loosen the nut. The first time this is attempted, the wrench should be held towards the end. Students will observe that it requires only a little force to loosen the nut. 3. Retighten the nuts and have each student repeat this exercise but by holding the wrench much closer to the bolt. Students will observe that this is much harder. 4. Use these observations to make several points: If the force is applied close to the bolt (short moment arm), students will observe that the nut can be turned only with difficulty, indicating a high torque. If the force is applied towards the end of the wrench handle, less force is required, indicating a lower torque. Another good way to demonstrate this concept is to have students try to push open a door by pushing on the handle. Then they should try to push open the door by exerting a force closer to the where the door is hinged. The same result can be observed.
GRADES 9-12 ★ UNIT 2 ★ PHYSICS • 33 Part 2: In this section, students will calculate the torque (t) acting on the drive shaft of a Monster Truck using the equation (t= Ia), where I is the moment of inertia of a rotating shaft (I = MR2/2 where M = the mass of a drive 2 shaft and R = the radius of the drive shaft) and a is angular I=MR /2 acceleration.
1. Given values of M = 13.61 kg and R = 0.04 m, instruct students to compute the moment of inertia for a drive shaft. 2. Explain to students that the average angular acceleration can be calculated by this equation:
a = (vf -vi )/t π where “vi ” is the initial angular velocity [= 2 (RPMdriveshaft/60 seconds)] when shifting from one gear to the next (approx. 1500RPM); “vf ” is the final angular velocity π [=2 (RPMdriveshaft/60 seconds)] when shifting from that gear to the next; (approx. 8500 RPM); and “t” is the time to accelerate from one gear to the next (approx. 5.5 seconds).
3. Give your students values for RPMdriveshaft and “t” and have them compute the average angular acceleration. 4. Using the values computed in Steps 1-3, have your students calculate the torque acting on the driveshaft.
Part 3: In this final section, students can calculate the torque acting on a tire of a Monster Truck. Be sure to ask students why it is necessary to calculate both the torque of the drive shaft and the torque of a tire (a brief explanation of the interaction of the two may be necessary.)
1. Given the radius and mass of a Monster Truck tire (M = 800 lbs or 361.99 kg, R = 33 inches or 8.38 x 10-1 m), students should now calculate the moment of inertia for a Monster Truck wheel (I = MR2/2). 2. The average angular acceleration of a tire should then be calculated by this equation:
a = (vf - vi )/t π where “vi ” is the initial angular velocity [= 2 (RPMtire/60 seconds)] when shifting from one gear to the next (0 RPM at 0 mph); π “vf ” is the final angular velocity [=2 (RPMtire/60 seconds)] when shifting from that gear to the next; (304.1 RPM at 60 mph); and “t” is the time to accelerate from 0 mph to 60 mph (approx 4.5 seconds). 3. Using the values computed in Steps 1-2, students should calculate the torque acting on the wheel.
34 • Academic Extension/Modification: Advanced students can be asked to compute the forward speed of the Monster Truck using the following approach:
At a particular speed (70 mph), a Monster Truck tire rotates at 354.8 RPM and has a radius of 8.38 x 10-1 m. The π circumference of the tire will be computed using C = x 2r. The circumference can be multiplied by the RPMtire to obtain the distance traveled in one minute. The distance (in meters) traveled in an hour can be computed by multiplying the distance by 60. Students can convert this distance to miles/hour by dividing by 1610.
Writing Prompts/Potential Discussion Questions: 1. Given that pistons go up and down, speculate on how the oscillatory motion of pistons is used to make the camshaft rotate. 2. Given that the drive shaft runs the length of a vehicle, how is the rotation of the shaft transferred to the motion of a wheel that rotates on an axle perpendicular to the drive shaft?
• 35 THE PHYSICS OF COMBUSTION
Objectives: adiabatic Given the dimensions of a Monster Truck piston, students will Important Terms: compute the volume before and after the compression stroke and process, Carnot engine, coefficient of the change in temperature of the gas (Combined Gas Law). Then, kinetic friction, Combined Gas Law, given the combustion reaction of the engine and the energy four-stroke engine, First Law of released, students will note the change in volume and temperature. Thermodynamics Students will also learn to compute the work done by a piston (W = P DV). Exhibit Link: Curriculum Connection: This lesson serves as an excellent pre- exhibit activity, as it helps students This teacher-directed lesson provides a good review of key concepts understand what is happening behind such as thermodynamics, the Ideal Gas Law, heat capacity, work, and the scenes of a drive train. The energy. For this lesson students must first be introduced to a simple exhibit’s Shop area can then provide view of the four-stroke engine (intake, compression, power, exhaust). a look into these components of a The interesting physics angle is in the compression and power Monster Truck. strokes. Students will first explore a compression stroke’s role in the process of combustion, including how it illustrates the First Law of Thermodynamics and how some energy is lost to friction.
Next, students will examine the power stroke. Assuming complete combustion, the chemical reaction is:
2CH3OH + 3O2 2CO2 + 4H2O.
After developing a working knowledge of this chemical reaction as it pertains to combustion, students can calculate the work done in the power stroke (W = P DV). They will deduce that the difference between the actual work and the potential energy in a cylinder of methanol and air mixture can be explained only by a loss of energy due to friction between the piston and cylinder or heat loss in exhaust gasses.
Class Time: 50 minutes
Materials Needed: None
Lesson Steps: Note: A brief description of how a four-stroke engine works will be helpful before beginning the lesson steps. This can be done by drawing a Pressure versus Volume diagram on the board and briefly explaining the Carnot cycle. For the purposes of this lesson, the values of a Monster Truck piston have been estimated.
Part 1: Compression Stroke: After the cylinder is filled with a mixture of methanol and air (intake), the piston moves to the top of the cylinder, compressing the gas mixture. This compression causes a rise in temperature in the cylinder.
1. Instruct students to use the Combined Gas Law below to compute the increase in temperature:
P1V1/T1 = P2V2/T2
36 • GRADES 9-12 ★ UNIT 2 ★ PHYSICS The values on the left are initial values (when the piston is at the bottom of its compression stroke) and values on the right are final values (when the piston is at the top of the compression stroke). Supply the following values:
P1 = 1 atmosphere V1 = 1.11 L (volume of cylinder at the beginning of the compression stroke) T1 = 295° A (room temperature) P2 = 13.6 atmospheres (the exhaust pressure) V2 = 0.09 L (volume of cylinder at the end of the compression stroke) T2 = a value to be calculated by the student
2. Direct students to observe the increase in temperature and ask for the effects of this rise. (Answer: the efficiency of the combustion reaction is greatly increased.)
Part 2: Power Stroke: When the mixture is ignited (by a spark), a great percentage of the mixture is combusted, increasing the amount of energy converted from a chemical form (bonds in the methane and oxygen molecules) to kinetic energy of the piston. Assuming complete combustion, the chemical reaction is:
2CH3OH + 3O2 2CO2 + 4H2O
1. Write the reaction above on the board and instruct students to note the increase in the number of moles of gas (from 5 moles of reactants to 6 moles of products). 2. Note that the reaction releases heat, thus increasing the temperature of the gas. If available, have students look up the heat of combustion for the reaction in the Handbook of Chemistry and Physics. Assuming that about 5.5 x 10-2 moles of fuel are used per power stroke and the heat released in the combustion (DHc) = -726.34 kJ/mole, have students compute the energy released on each power stroke using the formula:
-2 energy released = Q = 5.5 x 10 x DHc
3. Students should then use the heat capacity equation (Q = mc DT) to calculate the increase in the temperature after combustion. Supply the following values:
Q = the heat released in the combustion, calculated in Step 2 m =4.37 grams (the mass of the exhaust gasses per power stroke) c = 0.32 kcal/kg C° (specific heat of the weighted average [in a ratio of 2:4—obtained from the stochiometry of the combustion reaction] for carbon dioxide and steam) DT = ? (the change in temperature of the air/methanol mixture before combustion and the carbon dioxide/steam mixture after combustion, to be computed by students)
4. The change in temperature (=DT) equals Tfinal - Tinitial, where Tinitial equals T2 computed by students in Part 1. Since they have just calculated the value of DT, students will calculate Tfinal. 5. Because the expansion of gasses in a power stroke occurs so rapidly, the process is nearly adiabatic. Hence the heat (Q) lost to the system is nearly zero.
• 37 The First Law of Thermodynamics is: DU = Q -W
where DU is the change in internal energy of the cylinder, Q is the heat added or removed to the system and W is the work done on the piston. Ask students to restate the first law as it applies to adiabatic processes. (Answer: DU = -W)
6. If DU = -W (negative means work is being done by the system) by determining DU, we have found the work done in the power stroke. Students should compute the work done by a piston in a power stroke using the equation (W = P DV), where P is the pressure (P2) computed in Part 1, and DV is the difference in volumes in that same step.
Academic Extension/Modification: Students can explore how lubricants reduce the coefficient of kinetic friction, thus improving engine efficiency and reducing engine wear. Alternately, they can consider the extent to which a real engine deviates from an ideal Carnot engine.
Writing Prompts/Potential Discussion Questions: 1. A Monster Truck engine is more efficient than a passenger car engine. How do the efficiencies compare with each other? How do the efficiencies of both types of engines compare to an ideal Carnot engine? Use the following equation and data table to compute the efficiency of a Carnot engine acting at the same operating temperatures in each vehicle: (Note: the values used below have been estimated.)
Efficiency = 1 -TL/TH
Temperature Differences for Carnot Comparisons
Blue Thunder Mazda Protege Low operating temp 295° A 295° A High operating temp 462° A 420° A
2. Some of the energy of the combustion reaction is lost because the exhaust gasses have such a high temperature. How much energy is lost to exhaust products?
3. Some of the energy of the combustion reaction is lost to friction between the piston and the walls of the cylinder. How does lubrication reduce this friction?
38 •
ENGINE OF THE BEAST
Objectives: Using the illustration provided, students will identify the camshaft, four strokes of an automobile engine. Students will Important Terms: understand and be able to explain how the four strokes, in crankshaft, engine block, exhaust valve, the appropriate order, will cause an engine to run. pistons, intake valve, spark plugs, timing chain or belt Curriculum Connection: This supplemental activity is best used during the study of Exhibit Link: engine fundamentals. The lesson can serve as an This lesson serves as an informative pre- introduction to the concept of the four-stroke engine, or as a exhibit activity. The exhibit’s Shop area review activity. The lesson corresponds to the NATEF Task examines the modifications and List, Section I on Engine Repair. specifications for Monster Truck engines. Upon visiting the exhibit, students will Class Time: be able to identify the Monster Truck 60 minutes engine as one that operates in a similar way to the engine in an automobile— Materials Needed: i.e., the four strokes are the same. They reproducible containing an illustration of the four strokes of will notice, however, that modifications an automobile engine have been made to the truck engine to increase horsepower and performance. demonstration engine where students can examine and view the four strokes demonstrated demonstration vehicle that can easily be prepared for students to see the operation of the four strokes [optional]
Lesson Steps: 1. Present students with the illustration of the four strokes, out of order and unlabeled. Then challenge students to arrange and label them correctly. 2. Have students share the order of strokes they chose, explaining why they were arranged that way. 3. Reinforce student answers that are correct and/or correct their misconceptions. Be sure to explain the reasons for the strokes being in a certain order, particularly if student answers in Step 2 do not adequately address the reasons. 4. Move students to the automotive lab to see the four strokes on an actual engine. If possible, use an engine in a demonstration vehicle to show how the four strokes actually operate. Be sure to explain to students that the engines used in Monster Trucks utilize this same four-stroke process. 5. To close the lesson and to help assess students’ understanding, ask students to explain the process and function of each of the strokes on the engine you use. Challenge students to explain what might happen if one of the strokes were to fail—how would this halt the process of the engine? The discussion questions can also serve as effective ways to close the lesson and assess students’ understanding.
40 • AUTOTECH ★ UNIT 3 ★ ENGINES Academic Extensions/Modifications: Divide the class into four groups and assign each group a stroke from the reproducible to explain or demonstrate. Groups could actually simulate the action taking place by their particular stroke. Remove the spark plugs from the engine so that students can hear the compressed air actually coming out of the spark plug hole. If you worry that students will struggle in Step 1, provide them with the labels for the four strokes, challenging students to put them in the proper order. Or, place the four strokes in the proper order and challenge students to label them correctly.
Potential Discussion Questions: 1. Why do the four strokes have to be in this order? 2. What device operates the valves? 3. Which stroke actually causes the crankshaft to turn? 4. Why does a Monster Truck also require four strokes?
Intake Compression Power Exhaust
• 41 The Power Behind Engines Label the strokes below and place them in the correct order.
REPRODUCIBLE A MONSTER TRUCK ENGINE IN MY CAR?
Objectives: Students will learn why it is important to know displacement, and BDC, bore, Important Terms: will practice using the formula for calculating it. Students will also displacement, horsepower, piston examine how to calculate engine size using rulers and precision stroke, TDC measuring tools.
Curriculum Connection Exhibit Link: Engine repair and engine performance are key topics that any auto This lesson serves as a good pre- technology class must cover. As part of a study of performance, it is exhibit activity. The exhibit Shop imperative that a technician understands how an engine generates area examines the modifications and horsepower as it relates to the displacement. In this lesson, students specifications for Monster Truck will practice using the formula provided to calculate engine engines. Students can apply the displacement of various motors. This lesson corresponds to the formula they learn to figure out the NATEF Task List, Section I on Engine Repair. displacement of engines on display in the exhibit. Class Time: 60 minutes
Materials Needed: engine block complete with crankshaft, connecting rods, and pistons paper, pencil, ruler, and calculator to calculate engine displacement illustration of a Monster Truck engine [optional] precision measuring tools, such as telescoping gauge, outside micrometer, bore gauge [optional]
Lesson Steps: 1. As a class, explore why it is important to be able to figure out an engine’s displacement. Allow at least a few different students to speculate on why they think it is important. (Some students may already know the answers to the question.) After gathering a few responses, indicate if their answers are correct (or close to being correct). Clarify that knowing an engine’s displacement is important because it is the foundation of an engine’s power—i.e., it indicates what power an engine starts with. If more power is needed (as is the case with Monster Trucks, for example), then the engine will need to be modified in order to create more horsepower. 2. Using their knowledge of the four-stroke engine, have students explain how they think that engine displacement is derived. (If preferable, students could even write short paragraphs on the questions you pose in Step 1 and Step 2.) 3. Provide students with the formula for calculating engine displacement: Total displacement = (Bore 2) x (stroke) x (0.7854) x (number of cylinders)
(Note that .7854 = pi/4) 4. You may want to give students some practice problems on paper before moving to the lab. The problems can be configured in different ways so that different values are missing. For example, students can work backwards, knowing that an engine’s total displacement is 350 cubic inches and that it has 8 cylinders, to determine the diameter of an individual cylinder. Additionally, you can challenge students with problems in which an engine is modified. For example, engines can be “bored out” by increasing each cylinder’s diameter by .060 of an inch. Similarly, a problem can contain an increased or decreased engine stroke.
AUTOTECH ★ UNIT 3 ★ ENGINES • 43 5. Move to the classroom lab. Depending on students’ knowledge of measuring tools, use the ruler or precision measuring tools to measure an engine block. Using the ruler will give the students the concept of how engine displacement is derived, but it is important to point out that precision tools should be used in an actual precision measurement for displacement. 6. Have students record their measurements and return to the classroom and calculate their findings. Check for understanding and correctness. You may wish to provide the additional sample problems in class or as homework. (Answers: 1) 37.5, 3.638 2) 454 cubic inches, 7.4 liters 3) 4.49 or 4.5
Academic Extensions/Modifications: Using diagrams and/or actual measurements taken from the Monster Trucks exhibit, have your students compare the displacement measurements for engines in standard vehicles vs. Monster Trucks. This lesson can also serve as a way to teach students how to use precision measuring tools. If you have several engine blocks available, divide the class into groups and allow students to measure several different engines. Have students convert their cubic inch measurements to liters, and/or cubic centimeters. After learning that the same displacement formula applies to all engines, have students research ways in which people modify engines, e.g., adding horsepower, turbo chargers, etc. They can summarize their findings and report them back to the class.
Potential Discussion Questions: 1. Why are different units of measurement, for example, standard and metric, used? 2. How do the displacement values of engines in Monster Trucks compare with those of standard vehicles? 3. How are the engines of Monster Trucks modified?
Additional Problems 1. A 4.90 liter V8 Cadillac has a 300 cubic inch engine displacement. What is the displacement of one cylinder? If the bore = 3.623 inches, what is the value of the stroke? 2. A standard 3 1/4 ton GM truck has 8 cylinders. If the cylinders measure 4.25 inches in diameter, and the stroke value is 4 inches. What is the total engine displacement? What is the displacement in liters? 3. Blue Thunder has a 8 cylinders, a 4.25 inch stroke and a displacement of 540.47 cubic inches. What is the bore value?
44 • SAFETY IS OUR GOAL
Objectives: Students will brainstorm safety precautions they feel are necessary eye wash when working in an auto shop. After reviewing the rules, students Important Terms: will conduct a mock safety inspection of their shop. station, fire extinguishers, jack stands, Material Safety Data Sheets (MSDS) Curriculum Connection Automotive safety is embedded in all NATEF tasks and is a Exhibit Link: required unit that all automotive students must complete in order This activity serves as an excellent pre- to be qualified to perform in an automotive lab. Being able to work exhibit lesson. The Monster Truck around an automobile and in an automotive shop safely is one of Safety Lab includes the USHRA safety the most important goals of any automotive student. Some prior guidelines, and danger and hazard knowledge of automotive safety is helpful for this lesson but not warnings are posted in the lab. As they required. view the Monster Truck exhibit, students could note any familiar safety Class Time: equipment they see being used around 60 minutes the exhibit to protect viewers, and also note any specialty safety equipment or Materials Needed: special rules they see specific to the Trucks Shop. General Safety Rules Checklist Starter automotive lab bugged with minor safety problems for students to find during inspection
Lesson Steps: Note: Prior to beginning this exercise, bug your automotive lab with some minor safety violations. Some violations should be more subtle than others.
1. Begin by asking students to brainstorm what they think are good safety rules to use in an automotive shop. List their responses on the board or overhead. Students should provide reasons why the safety rules they list are important. 2. Distribute the General Safety Rules Checklist Starter to students and identify how many rules they named are on the list. Make sure that students realize that the checklist is only a partial list of safety rules. Add more rules to the list based on their brainstorm. 3. Allow students to ask questions about the rules that are listed, making certain that they clearly understand them. As part of the discussion, ask students if they think that the safety rules apply in auto shops of all kinds. Further, ask them if they think certain shops—e.g., Monster Truck shops, NASCAR shops—likely have additional safety rules that are unique. 4. Divide students into groups. Instruct students to use their checklists to conduct an inspection of the automotive lab for any safety issues and to make note of what they find. 5. Have students return to classroom to share their findings and explain what is needed to correct the problems found.
AUTOTECH ★ UNIT 3 ★ SAFETY • 45 Academic Extensions/Modifications: Divide students into two groups: one group is assigned to go to the lab and create some minor safety problems, and the other group is charged with finding the safety violations. Challenge the group that initiates the problems to create violations that they think the other group will overlook. Have students create a drawing of a specialty automotive lab—e.g., Monster Truck or NASCAR lab— including the safety equipment they think is needed. If time permits, review specific MSDS you have on hand.
Potential Discussion Questions: 1. What are some important safety concerns in the automotive lab? What are some of the negative consequences that could result from not having rules in place? 2. What should you do when you find a safety violation in a lab? 3. Why do you think that so many safety rules and concerns are shared in many different kinds of labs?
46 • General Safety Rules Checklist Starter Use this checklist to inspect your automotive lab. Be sure to also note any violations you identify which are not included in this list. P=pass F= fail Violations ____ 1. Always wear safety glasses when working in an automotive shop.
____ 2. Never play around or “horseplay” in an automotive shop. It is extremely dangerous and could hurt or kill someone.
____ 3. Use tools only for what they were designed for; always clean and store them properly.
____ 4. Notify the instructor when a tool is broken or does not seem to operate properly.
____ 5. Notify the instructor immediately if an accident occurs.
____ 6. Obtain your instructor’s permission before using any power tool or lifting device.
____ 7. Keep safety guards on all power tools. Do not remove them for any reason.
____ 8. Maintain electrical cords on power equipment; never use cut or frayed insulation or exposed wires.
____ 9. Place jack stands under a vehicle any time it is jacked up, even if only for a few minutes.
____ 10. Clean up spills immediately and dispose of all waste fluids in a proper container.
____ 11. Ensure that fire extinguishers are always easily accessible and in working condition.
____ 12. Always wear protective clothing and gear to prevent damage to your face, hands, ears, body, and feet.
REPRODUCIBLE A SAFE RIDE ANYWHERE
Objectives: Students will identify and understand the active and passive active restraint systems on a vehicle. Students will also examine the Important Terms: unibody construction of a car and its built-in safety features. restraint, passive restraint, Supplemental Restraint System Curriculum Connection: (SRS), unibody design As a supplement to a unit focusing on automotive safety, this lesson examines the standard safety equipment and features provided on a Exhibit Link: vehicle to protect the driver and passengers in the event of an accident. This lesson is best utilized as a pre- exhibit activity. After examining Class Time: the safety features of a normal car, 45-60 minutes students can visit the Safety Lab in the exhibit in order to compare the Materials Needed: safety features of a Monster Truck demonstration vehicle and lift to show unibody construction and to to those of a car. demonstrate safety equipment demonstration items such as a seat belt including shoulder harness, and a deployed air bag
Lesson Steps: 1. Begin by showing students the seat belt and air bag that you have acquired. Ask them for input on how they work. Allow time for discussion. If students share any incorrect information, give other students the opportunity to correct the wrong information. When necessary, reinforce the correct use of the seat belt in order for the air bag to provide protection in the event of an accident. 2. Follow up the discussion of seat belts and air bags—two of the more obvious safety features—with other safety features on various vehicles. These may include anything from anti-lock brakes to active head restraints. (Hopefully in the discussion, students mention the body of the vehicle, which you will explore more deeply in the next step.) 3. Ask students to define “unibody construction” and explain why this type of construction is safer than earlier types of construction. Guide the discussion so that students understand how unibody construction is relatively lightweight and has built in “crush zones” to help absorb impact in the event of an accident. 4. Move to the automotive lab and have a demonstration vehicle on a lift so that students may examine how the unibody construction is designed. Show them the various parts that by design will absorb impact and make the vehicle safer. 5. After seeing how vehicle manufacturers have built in measures to improve safety, lower the vehicle to reinforce some of the behaviors that individuals can take to maximize their own safety. Ask for volunteers to get in the vehicle and demonstrate the correct use of seat belts. Students can be in the driver and passenger positions. Have remaining students examine and evaluate whether they are buckled in properly. 6. Locate where the air bags are in the demonstration vehicle and demonstrate with a student the proper positions for the driver, steering wheel, and passenger to maximize the effect of an air bag should it deploy. It is also important to review safety precautions to take if work is being done on the vehicle to avoid accidentally deploying the system. 7. For closure, have students relate the safety features of standard vehicles with those of Monster Trucks. Ask what special features a Monster Truck must have and what unique dangers Monster Truck drivers face.
48 • AUTOTECH ★ UNIT 3 ★ ENGINES Though the safety features of Monster Trucks may require some speculation on the part of students, they will still need to show their understanding of the safety of standard vehicles; thus providing you with an engaging way to assess their understanding.
Academic Extensions/Modifications: As mentioned in Step 7, comparing safety features of Monster Trucks with standard vehicles often results in a deeper understanding of the safety features of a standard vehicle. Have students research the safety components of a Monster Truck and provide a detailed comparison of safety features on standard vehicles and Monster Trucks. Make sure that they also explain the reasons for the specialty safety features on Monster Trucks. This lesson is an excellent opportunity for students to do some statistical research on how safety has improved since the implementation of safety requirements in the production of the automobile. Some available resources could be local law enforcement records, Insurance Audit Information sites, etc. Extending the lesson in this way could also involve skills that the students have learned in mathematics/statistics classes. If possible, you can deploy a driver’s air bag to give students an example of what one looks and feels like. Explain the detonating device and show how the air bag deflates after it has been inflated. [There are vent holes placed strategically in the air bag to allow the vapors to escape.]
Potential Discussion Questions: 1. What are some ways that the driver is protected in the event of an accident? 2. What are some safety devices on the automobile that you think you would also find in some form on a Monster Truck? 3. What safety equipment do you think the Monster Truck has that an automobile does not have?
• 49 Glossary
acceleration: a change in the direction circumference: the distance around a exhaust valve: the valve that opens to or magnitude (speed) of an object. circle. allow all the vapors inside the cylinder to be removed from the engine on the average acceleration: can be computed coefficient of friction: the ratio of the exhaust stroke. with this equation: a = (vf - vi)/t, force of friction to the normal force where “a” is the acceleration, “vi” is when one surface is sliding (or eye wash station: the area in a lab the initial speed, “vf” is the final speed, attempting to slide) over another specifically designed for washing any and “t” is the time it takes to change surface. foreign matter from the eyes; a station speed. can be plumbed into the water system Combined Gas Law: expression or may use separate bottles of saline active restraint: a type of safety relating pressure, volume, and solution. equipment activated by the vehicle temperature before and after an event passenger, designed to restrict the when the moles of gas remain fire extinguisher: hand-held fire movement of drivers and/or passengers. constant: P1V1/T1 = P2V2/T2. fighting equipment designed with (ex. seat belt, child safety seat specific chemicals to put out small fires. restraints) consume: to take in or use up; burn, as an automobile engine burns fuel to First Law of Thermodynamics: the adiabatic process: a thermodynamic move a vehicle. change in the internal energy of a process in which no heat is lost or system equals the difference between gained. The power stroke in an engine crankshaft: device that changes the the heat added to the system and work occurs so rapidly that little heat is lost; reciprocating motion of the pistons to done by the system. therefore, the power stroke is rotating motion; contains the area considered an adiabatic process. where the connecting rods are fastened four-stroke engine: an internal- and also the area where the flywheel combustion engine developed by angular acceleration: the change in and engine drive pulley are connected. Nikolaus Otto in 1867. A four-stroke angular velocity divided by time. engine works as follows: as a piston customary system of measurement: a moves down, the intake valve(s) angular momentum: the product of measurement system used in the opens, allowing a mixture of fuel and the moment of inertia and its angular United States, which includes basic air to flow into the cylinder (intake velocity. units such as feet and gallons. stroke). After the intake valve(s) closes, the piston moves upwards, angular velocity: for rotating objects, dashboard: the panel under a vehicle’s compressing the mixture and the amount of rotation expressed in front windshield, on which an increasing its temperature radians/time. automobile’s fuel gauge and other (compression stroke). If this mixture is control instruments display. ignited, the piston is driven BDC: the measurement of a piston at downwards, making the drive shaft the bottom of its travel in the cylinder. diameter: a line segment that passes rotate (power stroke). Lastly, the through a circle’s center to connect piston moves upwards while the bore: the diameter of a cylinder in an two points on the circle. exhaust valve(s) opens, allowing engine. exhaust gasses to be pushed out of the displacement: the distance between two cylinder. camshaft: the component that controls points. In auto technology, the volume the opening and closing of valves in an that a piston displaces in a cylinder as it gauge: a measuring device. engine. moves from TDC to BDC. horsepower: the measurement of the capacity: the amount a container or distance: the straight-line engine’s ability to perform work. object can hold or contain; e.g., the measurement between two points. amount of fuel a Monster Truck’s fuel intake valve: valve that opens to allow tank can hold. engine block: the metal foundation fuel and air to be drawn into the containing the parts of an internal- combustion chamber. Carnot engine: an ideal engine in combustion engine; includes cylinders, which each process is reversible. coolant passages, oil passages, etc.
50 • jack stands: safety devices designed to momentum: the product of an object’s speed: the rate of change in an object’s be placed under a vehicle that has been speed and its mass; p = mv. (plural: position over time (speed = jacked up to prevent the vehicle from momenta) distance/time). falling while work is being performed. net force: the sum of all the forces Supplemental Restraint System kinematics: the description of motion acting on an object. (SRS): restraints designed to help keep in terms of distance, speed, velocity, drivers and passengers in their and acceleration. passive restraint: a type of safety respective seats in the event of an equipment designed to restrict the accident. (ex. air bags) kinetic energy: the energy an object movement of drivers and/or passengers; has due to its motion. activates automatically to protect the TDC: the measurement of the piston occupant of a vehicle. (ex. air bags, at the top of its travel in the cylinder. Law of Conservation of Energy: automatic shoulder harness) states that the total energy in a system timing chain or belt: a device that both before and after a process is pi: a ratio of a circle’s circumference to coordinates the movement of the constant. its diameter, equal to about 3.14 (or 3). crankshaft with the camshaft to ensure that pistons and valves are working Law of Conservation of Momentum: piston stroke: the movement of the together. In an isolated system, if the momenta piston from the bottom of its travel to of two objects are measured before and the top of its travel. torque: a force applied to some point after colliding, the total momenta will other than the center of an object’s be the same. piston: the component in an engine mass, causing movement or rotation. that is driven up and down in the Material Safety Data Sheets (MSDS): cylinder and is connected to the unibody design: a chassis design that information provided by chemical crankshaft by the connecting rod. includes a floor pan and a small sub manufacturers that have instructions frame section in the front and rear. on how to protect users and the potential energy: the energy an object environment in case of a spill; also has due to its position. variable: a quantity that may have contains instructions on how to clean more than one value. up and dispose of material that has projectile motion: the motion of an been spilled. object in a gravitational field. velocity: speed in a particular direction. (e.g., 50 mph due north) If metric: the decimal-based radius: a line segment that connects a an object does not change its direction measurement system used most often circle’s center to any point on the of motion, then its speed is the same as in the United States during scientific circle; it is half the size of the diameter. its velocity. pursuits; basic units include meters and liters. rate: the measure of how fast work: the transfer of energy to a body something is changing; when the by the application of a force that moment of inertia: the product of the distance an object moves is divided by moves the body in the direction of the mass of a rotating object and its radius the time it takes to travel that force (W = Fd). squared. The exact equation depends distance, the quotient equals the on the shape of the object, but for object’s average rate of speed, e.g. feet drive shafts or tires, it is given by this per second. equation: MR2 /2 where M is the mass of the rotating object and R is its spark plugs: devices that, upon radius. The moment depends on the receiving power, ignite the fuel/air in mass of the rotating object and on how the combustion chamber causing the far from the axis of rotation the mass piston to move down in the cylinder, is. If the mass is close to the axis of and thus causing the crankshaft to rotation, the moment is small. If the turn. mass is far from the axis of rotation, the moment is large.
• 51 Additional Resources and Web Sites
Teacher References Giancoli, Douglas. Physics: Principles with Applications. 2nd Edition. © 2000-2001 by Prentice Hall Inc.
Halliday, D., Resnick, R., & Walker. Fundamentals of Physics. 5th Edition. © 1997 by John Wiley & Sons, Inc.
Hewitt, P. Conceptual Physics. 8th Edition. © 1998 by Benjamin Cummings.
Zitzewitz, P. Glencoe Physics: Principles and Problems. © 2002 by Glencoe/McGraw Hill.
Monster Truck Racing by Scott D. Johnston (Capstone Press, 1994) This book is a clear, concise, and colorful introduction to Monster Truck racing for grades 4-6 students. The author describes the history, science, economics, and sport of Monster Truck racing. The book includes many photographs, a glossary, and a list of additional resources.
Web Sites http://www.getbehindthewheel.com/index.htm This web site includes links to the web sites of automotive corporations, whose sites include detailed information about dozens of automobiles, including photographs you might wish to show students when discussing vehicles’ relative fuel capacities.
http://www.its-about-time.com Visit this site to learn more about the popular textbook line Active Physics and other supplemental kits available to teach math and science concepts to grades 6-12.
http://www.monstermania.com Find information about upcoming events, Monster Mania news, and links to Monster Truck Home pages here.
http://monstertruckracing.com. Access high-quality photographs of all your favorite trucks, plus read Truck facts and stats.
http://www.physicsclassroom.com/ A good resource for learning basic physics concepts and reviewing them in a Physics Tutorial. Also includes practice problems and a multimedia section where students can view physics in action.
http://www.sciencejoywagon.com/physicszone/ The Physics Zone presents introductory level, algebra-based physics concepts in a multimedia format that is engaging as well as informative.
http://www.truckworld.com/index.html Read monthly articles written by experts and view the Show and Events section for all the latest results.
http://ushra.com/# Official site of the USHRA, this resource provides current Monster Truck results, a photo gallery, official news and headlines, driver bios and more. A true Monster Truck fan must-see!
52 •