Pulleys UNIT: PULLEYS OVERVIEW

INTRODUCTION In this unit students will build on their knowledge of Simple Machines by building a pulley frame that can lift weights and also a block and tackle system that raises the arm of a Crane.

STANDARD NCF ALIGNMENT

SCIENCE

• Idea of force-push or pull; change in speed, direction of moving objects

MATHEMATICS

• Conversion of units of length between smaller and larger units

ENGLISH LANGUAGE ARTS

• To be able to articulate individual/personal responses effectively

• To use his/ her proficiency in English to explore and study other areas of knowledge through print and non-print media

• To be able to narrate simple experiences, describe objects and people, report events to peers

1 Pulleys OVERVIEW

CREYA OUTCOMES

ANALYTICAL THINKING COLLABORATION

• Analyzing information: data, ideas, or concepts • Contribution to team

• Applying formulae, procedures, principles, or themes • Working with Others

• Presenting multiple solutions, positions or perspectives • Time Management

CREATIVE THINKING INFORMATION FLUENCY - JOURNALING

• Ideation/Brainstorming • Format • Mechanics • Originality • Proper spelling and grammar • Flexibility in approaches INFORMATION FLUENCY - INFORMATION LITERACY PROBLEM SOLVING • Access the needed information • Define the problem

• Identify Strategies

• Propose solutions/Hypotheses

• Implement the solution

2 Pulleys PREPARATION

PROJECT 1: PULLEY FRAME PROJECT 2: PULLEY CRANE

Overview: Overview: In, Pulley Frame, students will build a frame and lift a In the, Pulley Crane, students will use a block and load with pulley systems. tackle system to raise and lower a crane arm.

Materials: Materials: 4 - Hinged Block Claw 4 - Tire 45 1 - Clip Axle 45 15 - Building Block 30 4 - Hub Nut 1 - Axle Coupling 2 - Building Block 15 4 - Hinged Block Claw 2 - Clip Axle 75 2 - Building Block 15 with 2 Pins 4 - Spacer Ring 1 - Crank Shaft 4 - Building Block 15x30x5 with Groove 9 - Building Block 15 with Bore 5 - Bearing Sleeve and Pin 15 - Building Block 30 2 - Building Block 7.5 4 - Bearing Sleeve 2 - Building Block 15 with 2 Pins 3 - Clip 5 1 - Bottom Plate 30x90 4 - Flat Hub Collet 1 - Mounting Plate 15x45 1 - String 2 - Clip Axle 30 1 - String

Preparation Tips: Preparation Tips: Be gentle with raising and lowering the load on the pulley frame. Rough usage Pay attention to which pulley the string rests on. with the pulley system can break the frame.

3 Pulleys BACKGROUND

About Pulleys

How do you raise a flag on a tall flagpole, without machine is the number of times a machine multiplies standing on top of it? Most flagpoles use a pulley. A the effort, and is the ratio of the output force to the pulley is a simple machine made with a rope, belt, input force. A moveable pulley rises and falls with the or chain wrapped around a grooved wheel or similar load that is being moved and creates a mechanical device. Pulleys are generally used to raise, lower, or advantage. A combination of fixed and move a load. A pulley changes the direction of the moveable pulleys in a block and tackle pull, or effort. When you pull down on a flagpole’s also creates mechanical advantage and rope, the flag will rise. A single pulley makes a job reduces the amount of effort needed to pull up a load. Block and tackle system allows heavy object to be lifted with less force. In a block and tackle, the rope must be pulled a greater distance as it winds through several sets of pulleys. The trade-off for less effort is more rope pulled.

seem easier by letting you pull with the force of gravity instead of lifting against it. For example, you If you are pulling down on a rope are asked to raise a 50 kilogram weight. If you tie a on a block and tackle system, the 1 2 rope to the weight and try to raise it, you have to pull mechanical advantage is equal to up something weighing 50 kilograms. If you run the the number of ropes supporting the rope around a pulley, you are pulling down; it seems load. Count each end of the rope as slightly easier because you can use your own weight a separate rope. as a counterweight. A fixed pulley does not rise or fall with the load being moved, and does not create a For example, two rope ends support a moveable mechanical advantage. pulley which is connected to a 100 kilogram weight. The mechanical advantage is 2 and in this situation, One of the properties of a simple machine such as the an effort force of 50 kilograms will lift a resistance pulley, is that is it can be used to magnify the force force of 100 kg. applied to a task. The mechanical advantage of a

4 Pulleys BACKGROUND

Terms BLOCK AND TACKLE A block and tackle is a tool often used to lift heavy or hard to reach objects. It consists of two basic parts. The block is a pulley or set of pulleys fitted in a frame. The block is usually attached to a stationary object. The tackle is the rope or cable that runs through the block and anything else needed to make the machine work. Some tackles, like the one in the picture, use moving pulleys as well as the rope. The rope will move through the block and, together, the block and tackle can be used to help one person lift a lot more than they could without it.

FIXED PULLEY A fixed pulley is a pulley that is fixed into one place.

MOVEABLE PULLEY A moveable pulley is a pulley that moves along a rope or chain as it is pulled. It is the opposite of a fixed pulley.

PULLEY A pulley is a wheel with a groove around the edge. Pulleys can be used as a simple machine to change the direction of a pulling force. By throwing a rope or chain over a pulley, you can lift something up by pulling down.

MECHANICAL ADVANTAGE Mechanical advantage is the upper hand you gain when you use a mechanical device or machine to help you multiply the amount of force you can transmit. Mechanical advantage is expressed mathematically as a ratio or fraction. The top number of the fraction is the force the machine puts out to perform the work you’re trying to do. This top number is therefore called the output. The bottom number of the fraction is the force you have to put into the machine to make it do the work, and we call this number the input.

“WOW” Exercises The following is a class demonstration that allows students to experiment with pulleys. 1. You will need a broom handle or other rigid dowel, duct tape, a length of rope, and a liquid detergent jug filled with water. 2. Ask students to lift the jug straight up using the rope and broom handle. Have students share their results. 3. Tape the ends of the broom handle down between two desk tops or other appropriate surfaces. Tie one end of the rope to the broom hand and loop the rope through the jug handle. Loop the rope around the top of the dowel, back through the jug handle and loop again around the top of the dowel again. The jug handle will act as a movable pulley. 4. Have students lift the jug by the free end of the rope. Have students compare the effort between lifting the jug, and using the pulley system to lift the jug. 5. Compare the amount of rope used lifting the jug with one loop around the dowel, and the amount of rope used with the two loops. Does one system use more rope than the other?

5 Pulleys PROJECT 1: PULLEY FRAME

Materials

15 - Building 2 4 - Building Block 15x30x5 1 - Bottom 4 - Bearing 4 - Hinged 2 - Building 1 - String Block 15 Block 30 - Building Block 15 with Groove and Pin Plate 30x90 Sleeve

Build

In this project, you Place a Bottom Plate 1 will build a frame and 3 30x90 over the pairs of experiment with lifting Building Block 15x30x5 a weight with a single with Groove and Pin. pulley system. You will compare it to lifting the weight with a multiple pulley or block and tackle system.

Start by building the Position two Building 2 frame supports. Take four 4 Block 15s with 2 Pins Building Block 15x30x5s on the frame support with Groove and Pin and and mount five Building connect two of them Block 30s on each of the together to form two sets Building Block 15s with 2 of two. Pins.

6 Pulleys PROJECT 1: PULLEY FRAME

Place Building Block 15 on Place two Hinged Block 5 each of the two columns. 8 Claws on top of the Fix two Building Block 30s Building Block 30. between the two Building Block 15s.

Attach a Hinged Block 6 Claw with Bearing Sleeve beneath each of the two Building Block 30s. These Bearing Sleeves and Hinged Block Claws will serve as fixed immovable pulleys in a block and Insert a Bearing Sleeve tackle. Set the frame 9 into each of the Hinged aside. Block Claws.

Start the moveable pulley 7 piece of the block and tackle. Place a Building Block 30 on top of two vertically placed Building Block 30s.

7 Pulleys PROJECT 1: PULLEY FRAME

Place the moveable pulley 10 component between the upright posts of the support frame.

Finished.

Run a string from one 11 of the Bearing Sleeves on the moveable

pulley component up 4 to one of the Bearing 2 3 Sleeve components on the frame. Run the string back down to the 1 second Bearing Sleeve on the moveable pulley component and up and over the second Bearing Sleeve component on the frame.

8 Pulleys JOURNAL

Pulley Frame Name: ______Date: ______

1. Pull the string and make sure it glides smoothly. 5. With the string passing over just one pulley, calculate the length of string that you have to pull to lift the weight 10 cms. Express your answer in metres. 2. Redo the string so that it is connected to the weight and ______then goes over just one of the frame’s Bearing Sleeves. Try ______lifting and dropping the weight several times. Which seems ______easier? One pulley or the block and tackle? ______Single Pulley: o Block and Tackle: o ______

3. Repeat the exercise for each pulley system several times. Is there a difference in 6. Now repeat this exercise with the original finished model. What is the length of the amount of string or the distance you must pull to lift the weights up to the the string that you have to pull to lift your weight 10 cms? Express your answer same height? Which system used a greater length of string? in metres.

______Single Pulley: o Block and Tackle: o ______4. Look up the definition of pulley using a dictionary or any other resource. ______Define this term in your own words: ______7. How is the mechanical advantage calculated in a pulley? Write down in your own words. ______9 Pulleys JOURNAL

Name: ______Date: ______

8. Observe the following 4 figures. Now calculate the mechanical advantage of each pulley system and write it down in the journal below.

a b

______

c d

______

10 Pulleys PROJECT 2: CRANE

Materials

4 -Tire 45 4 - Hub Nut 4 - Spacer Ring 2 - Building Block 15 1 - Mounting 2 - Clip Axle 30 2 - Clip 1 - Crank Shaft 2 - Building with 2 Pins Plate 15x45 Axle 75 Block 7.5

9 - Building Block 4 - Hinged 15 - Building Block 4 - Flat Hub Collet 1 - Clip 1 - String 1 -Axle 3 - Clip 5 5 - Bearing 15 with Bore Block Claw 30 Axle 45 Coupling Sleeve

Build In this project, you will Add the Claw-Sleeve 1 build a model that uses 3 combinations to two the form of a block and connected Building Block tackle to raise and lower 15s with 2 Pins as shown. the boom arm of a crane. You will build a model that integrates pulleys.

Start with inserting Construct two beams 2 bearing sleeves into two 4 each with three Building Hinged Block Claws. Block 30s, and join them together with the above assembly.

11 Pulleys PROJECT 2: CRANE

Add a Building Block 15 Add a spacer ring and 5 with Bore onto each end 7 then a Flat Hub Collets to of the two beams. Align all four ends of the axles. the bores horizontally. You may need to rotate the model to make yours match the diagram.

Slide a Clip Axle 75 Place a Tire 45 and Flat 6 through the rear 8 Hub Collet onto each Building Block 15 with Hub Nut. Secure them by Bore. Place a Building twisting tightly. Block 15 with Bore between the front-most Building Block 15s with Bore and lock the axle into place with a Clip 5.

12 Pulleys PROJECT 2: CRANE

Place two Building Block Construct a handle of the 9 30s on the rear end of the 12 pulley with a Crank Shaft crane. and a Bearing Sleeve. Set the vehicle aside.

Add Building Block 15 To start the boom arm, 10 with Bore and Building 13 connect five Building Block 7.5 on each of the Block 30s together. On two rear end columns. one of the ends attach Insert Clip Axle 30 from a Building Block 15 with each of the two Building Bore with the bore facing Block 15s with Bore and horizontally. Insert a Clip join the two Axles with an Axle 45 into the Building Axle Coupling. Block 15 with Bore.

Place a Mounting Plate Add two Hinged Block 11 15x45 over the two 14 Claws with Bearing Building Block 15s with Sleeves on the second Bore. Lock the right Clip Building Block 30 from the Axle 30 with a Clip 5. top.

13 Pulleys PROJECT 2: CRANE

Attach the boom arm to Tie a piece of string to 15 the central Building Block 18 the Clip Axle 30, and loop 15 with Bore with the the string from the Clip Hinged Block Claw facing Axle 30 around the upper upwards. Bearing Sleeve on the boom arm, back down to the first Bearing Sleeve on the crane chassis, back up to the lower Bearing Sleeve on the boom arm, and back down around Place a Building Block 30 the second Bearing Sleeve perpendicular to another 16 on the crane chassis and horizontal Building Block tie it there. 30. Place a Building Block 15 with Bore on the top of the Building Block 30.

Finished.

Add the beam-block 17 combination to the end of the boom arm. Lock both sides of the Clip Axle 45 with a Clip 5.

14 Pulleys JOURNAL

Crane

1. Turn the Crank Shaft. Does the boom arm rise?

Yes o No o

2. Reverse the turning direction of the Crank Shaft. Does the boom arm lower?

Yes o No o

3. As you are turning the Crank Shaft, watch the string as it runs around the Bearing Sleeves. Do the Bearing Sleeves turn as the string travels over them?

Yes o No o

4. Read a definition of Block and Tackle using a dictionary or the Creya Term Library. Define this term in your own words: ______

15 Pulleys CHALLENGES

CHALLENGE 1 CHALLENGE 2

Weightlifting Challenge: Using your knowledge of pulleys, build a pulley Extending Ladder: Pulley systems are used in many different machines. For system capable of lifting 5 kg or more. example, extending or telescoping ladders often have a pulley system. Use your knowledge of pulley systems to build an extending ladder using pulleys. Hints... Use Flat Hub Collets and Hub Nuts to create a pulley. Hints... Wrap string around pulleys located at the end of the ladder support to pull the extending part of the ladder forward.

16 Pulleys JOURNAL

Challenge 1 Name: ______Date: ______

1. Were you able to build a pulley system that could lift about 5 kg? If yes, write a paragraph describing what you did to meet the challenge. If no, describe the biggest problem that prevented you from succeeding at the task. ______

2. Describe a situation in which a pulley system would be useful. ______

17 Pulleys JOURNAL

Challenge 2 Name: ______Date: ______

1. How have you used, or planned to use, pulleys in building your extending ladder? Sketch the model in the box provided below.

2. Describe a job or a career that may use an extending ladder. ______

______

18 Pulleys CAPSTONE

Create a pulley system that can be used to deliver messages across the room. You may use fixed pulleys or a block and tackle and your invention may be motorized.

19 Pulleys JOURNAL

Capstone Name: ______Date: ______

The design process is a systematic problem-solving strategy used to 4. DESCRIBE your system: develop possible solutions to a problem and to narrow down the possible ______solutions to one choice. Several steps of the design process include answers ______to the following questions: ______1. DESCRIBE at least three different possible designs you could create. ______These potential projects should all involve the application of a pulley system. ______

a. ______5. SKETCH your system:

b. ______

c. ______

2. CHOOSE one of the potential projects. DESCRIBE why you chose this one: ______

3. CONDUCT RESEARCH on your proposed system. List three sources of 6. Describe building your model: information you used: ______a. ______b. ______c. ______

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