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2. 1. The unit of work is the A. second. B. newton. C. meter. D. joule. E. watt.

3. 2. The amount of potential energy possessed by an elevated object is equal to A. the power used to lift it. B. the value of the acceleration due to gravity. C. the work done in lifting it. D. the force needed to lift it. E. the distance it is lifted.

4. 3. Suppose a moving car has 4,000 J of kinetic energy. If the car’s speed doubles, how much kinetic energy will it then have? A. 2,000 J B. 4,000 J C. 8,000 J D. 12,000 J E. 16,000 J

5. 4. A student does 6000 J of work in 30 seconds. What is her power output?

6. 5. In physics, work is defined as A. distance divided by time. B. force divided by time. C. force times time. D. force times distance. E. force divided by distance.

7. 6. Can a machine ever be 100% efficient? Why or why not?

8. 7. A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but different amounts of A. power. B. energy. C. both A and B D. none of the above

9. 8. When energy changes from one form to another, the total amount of energy stays the same. A. Always true B. Sometimes true C. Always false

10. 9. Gravitational potential energy is the energy an object has because of its A. temperature. B. speed. C. density. D. elevated position. E. size.

11. 10. If you lift one load up one story, how much work do you do compared to lifting two loads up one story? A. One half as much B. Twice as much C. One quarter as much D. Four times as much E. The same amount

12. 11. A frictionless inclined plane is 10 m long and rests on a wall that is 2 m high. How much force is needed to push a block of ice weighing 500 N up the plane? A. 50 N B. 100 N C. 250 N D. 500 N E. 1000 N

13. 12. A small boy pushes a toy bulldozer with a force of 5 N over 2 meters. How much work did he do?

14. 13. As a pendulum swings back and forth, A. potential energy is transformed into kinetic energy. B. kinetic energy is transformed into potential energy. C. at the end points of its swing, its energy is all potential. D. at the lowest part of its swing, its energy is all kinetic. E. all of the above

15. 14. What is the gravitational potential energy of a 3-kg monkey hanging from a branch 5 m above the ground?

16. 15. A machine puts out 200 joules of work for every 1000 joules put into it. The efficiency of the machine is A. 10 %. B. 20 %. C. 80 %. D. 500 %. E. none of the above

17. 16. What is the kinetic energy of a 2-kg ball traveling at 3 m/s?

18. 17. The ratio of output force to input force of a simple machine is called the A. fulcrum. B. efficiency. C. pivot point. D. lever arm. E. mechanical advantage.