Name ____________________________

Phy.2.1 ReviewPhy.2.1.1 Interpret data on work and energy presented graphically and numerically.

1. A horizontal force, F, is used to pull a 5.0-kg block across a floor at a constant speed of 3.0 m/s. The frictional force between the block and the floor is 10 N. What is the work done by the force in 1 minute?

2. A force moves an object in the direction of the force. Using the force versus position graph shown, determine the work done when the object moves from 2.0 m to 4.0 m.

3. A student pulls a sled across level snow with a force of 225 N with a rope that is 35˚ above the horizontal. If the sled moved a distance of 65.3 m, how much work did the student accomplish?

4. 50 J of work is used to push a 1.8 kg box up an incline at an angle of 15˚ to the ground. The box is pushed from rest at the bottom of the incline to rest at the vertical height of 2.4 m. How much work is done against friction?

5. Neglecting friction, if a child exerts a force of 85 N on the handle of a wagon that makes a 35˚ angle with the horizontal, how far is the wagon pulled when 280 J or work are done?

6. If a forklift raises a 76 kg load a distance of 2.5 m, how much work has it done?

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Name ____________________________

Phy.2.1.2 Compare the concepts of potential and kinetic energy and conservation of total mechanical energy in the description of motion of objects.

7. The diagram below shows a rock with a mass of 5 kg on the edge of cliff where the height of the cliff, h, is 130m. If the rock rolls off the cliff, what is the kinetic energy of the rock just before it hits the ground? What is the velocity of the rock just before it hits the ground?

8. A ball is released from the top of an inclined plane as shown below. Ignoring friction, where will the potential energy (PE) and kinetic energy (KE) of the ball be at a maximum?

9. A 58-kilogram pole vaulter needs to vault a height of 6.0 m. Assuming that all his kinetic energy can be used for the vault, what is the speed that the vaulter must be traveling in order to clear this height? Ignore elastic PE of the bent pole.

10. A 2.0 kg book falls from a 1.5 m high shelf. What will be the velocity of the book as it hits the floor?

11. A 290-N force is used to compress a spring. The spring constant of the spring is 5,880 N/m. How far is the spring compressed?

12. A 588-N person carrying 294 N of equipment starts climbing a mountain that is 3,118 m high. What is the minimum energy required for the person to climb the mountain?

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Name ____________________________

13. A student drops a 0.45-kg ball that hits the floor with a speed of 5.3 m/s. If the velocity of the ball is 4.8 m/s when it hits the floor on the second bounce, how much mechanical energy is lost during the first bounce?

14. A pendulum swings back and forth up to a maximum height of 1.52 m. Neglecting friction, what is the speed of the pendulum at the lowest position?

15. How high can a worker lift a 40.00 kg bag of sand if he produces 4,000 J of energy? Assume no energy is used to overcome friction.

Phy.2.1.3 Explain the relationship among work, power and energy.

16. A student throws an object downward. The initial kinetic energy of the object is 360 J. When the object reaches the ground, the kinetic energy of the object is 3 times the initial kinetic energy of the object. What was the initial potential energy of the object?

17. The chart represents the work output and the time to do the work for four machines. Calculate the power output for each machine.

18. Which is a correct statement about the relationship between work, energy and power?a. Work transfers energy. Power is the rate at which work is done or energy transferred. b. Work is only done when an object is moved. Energy and power are the same quantity. c. Power is measure of how much work can be done. Energy is a measure of the time interval in

which the work is done. d. Energy and power are a measure of the amount of force while work is related only to the distance

an object moves. 3

Name ____________________________

19. What is the maximum velocity at which a 25-W motor can lift an 8.5 kg object upward?

20. A machine lifts a 35-kg object 20.0 m in 2.0 s. How much power is produced by the machine to lift the object?

21. How much power is required to lift a 12-Newton box at 4.5 m/s?

22. A 3.0 kg mass slides down a 5.0 m long frictionless, inclined plane. How much work is needed to stop the mass at the bottom of the incline?

23. A 650 kg car traveling at 5 m/s was stopped by applying the brakes. How much work did the brakes do when stopping the car?

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