Name: Curt Blimline Contact Info: [email protected] Date:24-Jun-13
Lesson Title: Zipline Basics Unit #: Lesson #: Activity #: Worksheet: c Activity Title: Zoom Zoom Activity 4 1 2 Worksheet Title: Zoom Zoom Activity Worksheet
Zoom, Zoom Name ______
http://www.piiholozipline.com/gallery/
Background
This activity is designed to explore the forces involved in zip line propulsion. There are gravitational forces and frictional forces to investigate. By resolving the forces involved, on can predict the acceleration of a zip line rider. Free body diagrams are used to express the forces that exist on a zipline and identify the net forces parallel and perpendicular to the zip line wire.
Objectives
1. After completing this laboratory investigation, the student will be able to
a. accurately draw the vector components of a force in two dimensions through use of a free body diagram.
b. mathematically calculate the vector components of a force in two dimensions.
c. determine the acceleration of a zip line trolley experimentally using motion sensors.
1 d. determine the friction on the trolley system mathematically.
Materials/Equipment (per team)
Computer with Logger Pro software installed – 1 Index card (4x6) – 1 Masses – assortment from 100 g to 1 kg Motion detector – 1 Pulley – 1 Galvanized steel wire (1/8” diameter) – 3 m Tape Vernier LabPro or Go Motion cable – 1
Procedure
1. Attach a motion detector to the LabPro and the LabPro to the computer. Set the switch on the motion detector to Track.
2. Open Logger Pro on the computer. Open the “Cart” file from the Physics with Computers folder. Blank position vs. time and velocity vs. time graphs should appear on the screen.
3. Set the time for 5 seconds and the samples/second to 30.
4. Mount the motion detector at the top of the zip line incline and focus it down the incline. You may have to make adjustments in its alignment prior to collecting data.
5. Measure the length and height of the incline and record in the data table.
6. Attach a mass to the zip line trolley and attach an index card to the mass perpendicular to the pulley on the trolley.
7. Move the trolley to the top of the incline. Position another team member at the other end of the incline to catch the trolley.
8. Select Collect in Logger Pro.
9. Release the trolley to collect and graph data relating to its motion. Make sure that the motion detector is sensing the motion correctly as it moves down the incline. If not, realign the motion detector until it tracks the trolley most of the way down the incline.
10. Store the latest run in Logger Pro.
11. Repeat steps 5-8 with two different masses. Data Table
Trial 1 Trial 2 Trial 3
Height of incline (m)
Length of incline (m) Mass including trolley (kg)
Data Analysis
1. Draw a free body diagram of the forces on the trolley system as it moves down the zip line. Include all of the forces that act on the trolley system.
2. Calculate the angle of the incline using the sine function and your data.
3. Find the normal force acting on the trolley system.
4. Find the parallel force on the trolley system due to its mass.
3 5. Calculate the expected acceleration of the mass and trolley in the absence of friction. Data Analysis Table
Trial 1 Trial 2 Trial 3
Angle of incline (o)
Normal force (N)
Parallel force (N) Expected acceleration – No friction (m/s2) Average acceleration from graph (m/s2) Calculated friction and drag forces (N)
Questions to Answer
1. What effect does the mass have on the normal force?
2. What effect does the mass have on the parallel force?
3. What effect does mass have on the frictional force of the trolley system?
4. What effect does the mass have on the acceleration of the zip line trolley?
5 5. What effect does the sag in the zip line have on the acceleration of the zip line trolley?
6. What effect does the angle of the zip line have on the acceleration?
7. Design a process that can be used to test your hypothesis?