Physics final answer key for students PDF

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Physics 2020-2021 Spring Semester Exam Review Part 1 Multiple Choice ____ 1. Mechanical energy can be in the form of D a. neither kinetic nor potential energy. b. potential energy. c. kinetic energy. d. both kinetic and potential energy.

3J ____

2. A 60-N object moves at 1 m/s. Its kinetic energy is

watt ____

3. The unit of power is the

____ C

4. In physics, work is defined as a. force times time. b. force divided by time. c. force times distance. d. distance divided by time.

A ____

5. How much power is expended if you lift a 60 N crate 10 meters in 1 second? a. 600 W b. 10 W c. 0 W d. 6 W

____ 20J

6. How much work is done on a 20-N crate that you lift 2 m?

25J ____

7. How many joules of work are done on a box when a force of 25 N pushes it 3 m?

____

8. When a car’s speed triples, its kinetic energy

increases by 9 ____ B

9. Kinetic energy of an object is equal to a. its mass multiplied by its speed. b. one half the product of its mass times its speed squared. c. its mass multiplied by its acceleration squared. d. one half the product of its mass times its speed.

____ 10N 10. It takes 80 J to push a large box 8 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box?

____ 11. Which has greater kinetic energy, a car traveling at 30 km/h or a half-as-massive car traveling at 60 km/h?

both have the same kinetic energy

____ 0J 12. How much work is done on a 60-N box of books that you carry horizontally across a 6-m room?

____ 13. How much power is required to do 40 J of work on an object in 5 seconds? 8 watts

____ 14. The amount of potential energy possessed by an elevated object is equal to D a. the power used to lift it. b. the force needed to lift it. c. the distance it is lifted. d. the work done in lifting it. ____ 15. An arrow in a bow has 70 J of potential energy. Assuming no loss of energy to heat, how much kinetic energy 70J will it have after it has been shot?

C ____ 16. Power is defined as the a. distance divided by the time taken to move that distance. b. work done on an object divided by the time taken to do the work. c. work done times the time taken to do that work. d. force on an object divided by the time the force acts. ____ 17. Which requires more work: lifting a 70-kg sack vertically 2 meters or lifting a 35-kg sack vertically 4 meters?

both require the same amount of work ____ 18. Potential energy is the energy an object has because of its

position relative to some zero position. An object possesses gravitational potential energy if it is positioned at a height above (or below) the zero height. ____ 19. The unit of work is the

joule ____ 20. All simple machines ideally work on the principle that B a. impulse equals momentum change. b. work input equals work output. c. force equals mass times acceleration. d. total momentum before a collision equals total momentum after the collision. ____ 21. An object that has kinetic energy must have (list several possible answers)

momentum

____ 22. A heavy object and a light object are released from rest at the same height and time in a vacuum. As they fall, D they have equal a. momenta. b. weights. c. energy d. none of the above ____ 23. If Nellie Newton pushes an object with twice the force for twice the distance, she does…. (in terms of work)

4x the work

A ____ 24. 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 ____ 25. A ball is thrown into the air with 100 J of kinetic energy, which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is

less than 100J ____ 26. An object that has kinetic energy must be

moving A

____ 27. Energy is changed from one form to another with no net loss or gain. a. Always true b. Always false c. Sometimes true

B ____ 28. An object at rest may have a. momentum. b. energy. c. speed. d. velocity. ____ B 29. If an object has kinetic energy, then it also must have a. force. b. momentum. c. impulse. d. acceleration.

True/False

____ 30. Energy transforms from one form to another with no net loss or gain. T

T ____ 31. The energy an object has by virtue of its motion is its kinetic energy. T ____ 32. When we carry an object across a room, without lifting it or setting it down, we do no physical work on it. ____ 33. The rate at which work is done is called power. T

____ 34. The energy an object has by virtue of its location is its potential energy. T

T ____ 35. The unit of work is called the joule. ____ 36. The unit of power is the watt. T

____ 37. More power is needed to carry a heavy suitcase slowly up a flight of stairs than to carry the suitcase quickly F up the same flight of stairs.

____ 38. In physics, the amount of work done on an object is the product of the force exerted on the object times the F time the object moves....