Download work, power, and energy concept questions

WORK, POWER, AND ENERGY CONCEPT QUESTIONS
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. In physics, work is defined as
a. force times time.
b. force divided by distance.
c. distance divided by time.
d. force divided by time.
e. force times distance.
2. If you lift two loads up one story, how much work do you do compared to lifting just one load up
one story?
a. One quarter as much
b. One half as much
c. The same amount
d. Twice as much
e. Four times as much
3. If you lift one load up two stories, how much work do you do compared to lifting one load up
only one story?
a. One quarter as much
b. One half as much
c. The same amount
d. Twice as much
e. Four times as much
4. If Nellie Newton pushes an object with twice the force for twice the distance, she does
a. twice the work.
b. the same work.
c. four times the work.
d. eight times the work.
5. The unit of work is the
a. watt.
b. meter.
c. joule.
d. newton.
e. second.
6. Power is defined as the
a. force on an object divided by the time the force acts.
b. work done times the time taken to do that work.
c. work done on an object divided by the time taken to do the work.
d. distance divided by the time taken to move that distance.
e. force on an object times the distance the object moves.
7. The unit of power is the
a. newton.
b. meter.
c. joule.
d. second.
e. watt.
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8. Potential energy is the energy an object has because of its
a. density.
b. size.
c. location.
d. speed.
e. temperature.
9. The amount of potential energy possessed by an elevated object is equal to
a. the power used to lift it.
b. the distance it is lifted.
c. the force needed to lift it.
d. the work done in lifting it.
e. the value of the acceleration due to gravity.
10. Kinetic energy of an object is equal to
a. its mass multiplied by its acceleration squared.
b. one half the product of its mass times its speed squared.
c. its mass multiplied by its speed.
d. one half the product of its mass times its speed.
e. its mass multiplied by its acceleration.
11. How much farther will a car traveling at 100 km/s skid than the same car traveling at 50 km/s?
a. Half as far.
b. The same distance.
c. Twice as far.
d. Four times as far.
e. Five times as far.
12. An arrow in a bow has 70 J of potential energy. Assuming no loss of energy to heat, how much
kinetic energy will it have after it has been shot?
a. 0 J
b. 35 J
c. 50 J
d. 70 J
e. 140 J
13. Energy is changed from one form to another with no net loss or gain.
a. Sometimes true
b. Always false
c. Always true
14. As a pendulum swings back and forth
a. at the end points of its swing, its energy is all potential.
b. at the lowest part of its swing, its energy is all kinetic.
c. kinetic energy is transformed into potential energy.
d. potential energy is transformed into kinetic energy.
e. all of the above
15. When a car’s speed triples, its kinetic energy
a. remains the same.
b. triples.
c. increases by four times.
d. increases by nine times.
e. none of the above
____ 16. A woman can lift barrels a vertical distance of 1 meter or can roll them up a 2-meter long ramp to
the same elevation. If she uses the ramp, the applied force required is
a. 1 as much.
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b.
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2
as much.
c. the same amount.
d. 2 times as much.
e. 4 times as much.
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. energy.
b. power.
c. both A and B
d. none of the above
Which requires more work: lifting a 70-kg sack vertically 2 meters or lifting a 35-kg sack
vertically 4 meters?
a. Lifting the 70 kg sack
b. Lifting the 35 kg sack
c. Both require the same amount of work.
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
a. 100 J.
b. more than 100 J.
c. less than 100 J.
d. Not enough information given.
An object that has kinetic energy must be
a. at rest.
b. falling.
c. moving.
d. elevated.
Which has greater kinetic energy, a car traveling at 30 km/h or a half-as-massive car traveling at
60 km/h?
a. The 60 km/h car
b. Both have the same kinetic energy.
c. The 30 km/h car
A person on a roof throws one ball downward and an identical ball upward at the same speed.
The ball thrown downward hits the ground with 140 J of kinetic energy. Ignoring air friction, with
how much kinetic energy does the second ball hit the ground?
a. less than 140 J
b. 140 J
c. 280 J
d. more than 280 J
e. none of the above
____ 23. How many joules of work are done on a box when a force of 25 N pushes it 3 m?
a. 1 J
b. 3 J
c. 8 J
d. 25 J
e. 75 J
____ 24. How much power is required to do 40 J of work on an object in 5 seconds?
a. 0 W
b. 5 W
c. 8 W
d. 40 W
e. 200 W
____ 25. How much work is done on a 60-N box of books that you carry horizontally across a 6-m room?
a. 0 J
b. 6 J
c. 10 J
d. 60 J
e. 360 J
____ 26. How much work is done on a 20-N crate that you lift 2 m?
a. 0 J
b. 1 J
c. 2 J
d. 20 J
e. 40 J
____ 27. How much power is expended if you lift a 60 N crate 10 meters in 1 second?
a. 0 W
b. 6 W
c. 10 W
d. 60 W
e. 600 W
____ 28. Suppose a moving car has 3000 J of kinetic energy. If the car's speed doubles, how much kinetic
energy will it then have?
a. 1000 J
b. 1500 J
c. 3000 J
d. 6000 J
e. 12,000 J
____ 29. A 60-N object moves at 1 m/s. Its kinetic energy is
a. 1 J.
b. 3 J.
c. 60 J.
d. more than 60 J.