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Chapter 8 Work and Machines
CRCT Preparation
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Chapter 8 CRCT Preparation
1. Patrick is evaluating saws to buy for his lumber mill. He calculates work inputs and outputs for each saw. Which saw has the highest mechanical efficiency?
A saw A
B saw B
C saw C
D saw D
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Chapter 8 CRCT Preparation
1. Patrick is evaluating saws to buy for his lumber mill. He calculates work inputs and outputs for each saw. Which saw has the highest mechanical efficiency?
A saw A
B saw B
C saw C
D saw D
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Chapter 8 CRCT Preparation
2. Which of these common objects is a third-class lever?
A stapler
B chisel
C seesaw
D bottle opener
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Chapter 8 CRCT Preparation
2. Which of these common objects is a third-class lever?
A stapler
B chisel
C seesaw
D bottle opener
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3. How does a simple machine decrease the required input force?
A by changing the direction of the input force
B by increasing the distance through which the output force is exerted
C by increasing the distance through which the input force is exerted
D by decreasing the amount of work that is required
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
3. How does a simple machine decrease the required input force?
A by changing the direction of the input force
B by increasing the distance through which the output force is exerted
C by increasing the distance through which the input force is exerted
D by decreasing the amount of work that is required
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4. Kristin is looking for a doorknob that is hard to turn to keep her baby brother out of her room. Which of the following doorknobs should she choose?
A a doorknob with a wheel radius of 5 cm and an axle radius of 4 cm
B a doorknob with a wheel radius of 6 cm and an axle radius of 2 cm
C a doorknob with a wheel radius of 3 cm and an axle radius of 0.5 cm
D a doorknob with a wheel radius of 4 cm and an axle radius of 3 cm
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
4. Kristin is looking for a doorknob that is hard to turn to keep her baby brother out of her room. Which of the following doorknobs should she choose?
A a doorknob with a wheel radius of 5 cm and an axle radius of 4 cm
B a doorknob with a wheel radius of 6 cm and an axle radius of 2 cm
C a doorknob with a wheel radius of 3 cm and an axle radius of 0.5 cm
D a doorknob with a wheel radius of 4 cm and an axle radius of 3 cm
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Chapter 8 CRCT Preparation
5. A wheelchair ramp is 5.2 m long and 0.8 m high. What is the ramp’s mechanical advantage?
A 4.2
B 4.4
C 5.2
D 6.5
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Chapter 8 CRCT Preparation
5. A wheelchair ramp is 5.2 m long and 0.8 m high. What is the ramp’s mechanical advantage?
A 4.2
B 4.4
C 5.2
D 6.5
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6. Which of the following is true about the way a screw works?
A A small input force is applied over a short distance.
B A large input force is applied over a short distance.
C A small input force is applied over a long distance.
D A large input force is applied over a long distance.
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
6. Which of the following is true about the way a screw works?
A A small input force is applied over a short distance.
B A large input force is applied over a short distance.
C A small input force is applied over a long distance.
D A large input force is applied over a long distance.
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7. In this movable pulley, the input force is 20 N. What is the output force?
A 10 N
B 20 N
C 40 N
D 80 N
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
7. In this movable pulley, the input force is 20 N. What is the output force?
A 10 N
B 20 N
C 40 N
D 80 N
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8. A screwdriver is used to open a paint can. How are the magnitudes and directions of the input and output forces related?
A The output force is greater than the input force, and the directions of the forces are opposite.
B The output force is less than the input force, and the directions of the forces are opposite.
C The output force is greater than the input force, and the direction of both forces is the same.
D The output force is less than the input force, and the direction of both forces is the same.
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
8. A screwdriver is used to open a paint can. How are the magnitudes and directions of the input and output forces related?
A The output force is greater than the input force, and the directions of the forces are opposite.
B The output force is less than the input force, and the directions of the forces are opposite.
C The output force is greater than the input force, and the direction of both forces is the same.
D The output force is less than the input force, and the direction of both forces is the same.
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9. Which of the following is true of a simple machine in which the output force is greater than the input force?
A The mechanical advantage is less than 1.
B The directions of input and output forces must be the same.
C The amount of work required to accomplish a task is decreased.
D The input force is exerted over a larger distance than the output force is.
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
9. Which of the following is true of a simple machine in which the output force is greater than the input force?
A The mechanical advantage is less than 1.
B The directions of input and output forces must be the same.
C The amount of work required to accomplish a task is decreased.
D The input force is exerted over a larger distance than the output force is.
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10. A wheelbarrow is a second-class lever. Its wheel is the fulcrum, and its load is carried in a tray. What could be done to a wheelbarrow in order to make lifting and moving rocks easier?
A the handles could be shortened
B the wheel could be made larger and wider
C the distance between wheel and tray could be increased
D the tray could be moved so it is above the wheel
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
10. A wheelbarrow is a second-class lever. Its wheel is the fulcrum, and its load is carried in a tray. What could be done to a wheelbarrow in order to make lifting and moving rocks easier?
A the handles could be shortened
B the wheel could be made larger and wider
C the distance between wheel and tray could be increased
D the tray could be moved so it is above the wheel
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11. Jenna is responsible for moving pianos for the Augusta Symphony. What are two simple machines that Jenna and her crew could use to move a piano from the stage in the concert hall onto a high outdoor stage? Explain how each machine would help make moving the piano easier.
Chapter 8 CRCT Preparation
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11. Answer –
An inclined plane and a block and tackle could be used. The inclined plane would reduce the input force needed for moving the piano into a truck or onto a stage, making it easier to move the piano. However, the piano would have to be pushed a longer distance than the height of the stage or truck. The block and tackle would multiply the input force by 4 (or more), making it possible to lift the piano with less effort. However, the rope would have to be pulled four times farther than the height of the stage or truck bed.
Chapter 8 CRCT Preparation
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Chapter 8 CRCT Preparation
12. Jeremy is using a hose and a sprinkler to water the lawn. What simple machines is he using, and how do these machines make the job easier?
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12. Answer –
A screw and a wheel and axle are being used. Screws allow the faucet and hose and sprinkler and hose to be attached to each other easily. A wheel and axle on the faucet allows the water to be turned on easily.
Chapter 8 CRCT Preparation
