# Chapter 6: Work And Energy

82 Questions | Total Attempts: 299  Settings  • 1.
What is the correct unit of work expressed in SI units?
• A.

Kg m/s^2

• B.

Kg m^2/s

• C.

Kg m^2/s^2

• D.

Kg^2 m/s^2

• 2.
Can work be done on a system if there is no motion?
• A.

Yes, if an outside force is provided.

• B.

Yes, since motion is only relative.

• C.

No, since a system which is not moving has no energy.

• D.

No, because of the way work is defined.

• 3.
If you push twice as hard against a stationary brick wall, the amount of work you do
• A.

Doubles.

• B.

Is cut in half.

• C.

Remains constant but non-zero.

• D.

Remains constant at zero.

• 4.
A 50-N object was lifted 2.0 m vertically and is being held there. How much work is being done in holding the box in this position?
• A.

More than 100 J

• B.

100 J

• C.

Less than 100 J, but more than 0 J

• D.

0 J

• 5.
If you walk 5.0 m horizontally forward at a constant velocity carrying a 10-N object, the amount of work you do is
• A.

More than 50 J.

• B.

Equal to 50 J.

• C.

Less than 50 J, but more than 0 J.

• D.

Zero.

• 6.
A container of water is lifted vertically 3.0 m then returned to its original position. If the total weight is 30 N, how much work was done?
• A.

45 J

• B.

90 J

• C.

180 J

• D.

No work was done.

• 7.
Does the centripetal force acting on an object do work on the object?
• A.

Yes, since a force acts and the object moves, and work is force times distance.

• B.

Yes, since it takes energy to turn an object.

• C.

No, because the object has constant speed.

• D.

No, because the force and the displacement of the object are perpendicular.

• 8.
You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.
• A.

Work is + on the way up and + on the way down.

• B.

Work is + on the way up and - on the way down.

• C.

Work is - on the way up and + on the way down.

• D.

Work is - on the way up and - on the way down.

• 9.
The area under the curve, on a Force versus position (F vs. x) graph, represents
• A.

Work.

• B.

Kinetic energy.

• C.

Power.

• D.

Potential energy.

• 10.
On a plot of Force versus position (F vs. x), what represents the work done by the force F?
• A.

The slope of the curve

• B.

The length of the curve

• C.

The area under the curve

• D.

The product of the maximum force times the maximum x

• 11.
The quantity 1/2 mv^2 is
• A.

The kinetic energy of the object.

• B.

The potential energy of the object.

• C.

The work done on the object by the force.

• D.

The power supplied to the object by the force.

• 12.
If the net work done on an object is positive, then the object's kinetic energy
• A.

Decreases.

• B.

Remains the same.

• C.

Increases.

• D.

Is zero.

• 13.
If the net work done on an object is negative, then the object's kinetic energy
• A.

Decreases.

• B.

Remains the same.

• C.

Increases.

• D.

Is zero.

• 14.
If the net work done on an object is zero, then the object's kinetic energy
• A.

Decreases.

• B.

Remains the same.

• C.

Increases.

• D.

Is zero.

• 15.
A truck weighs twice as much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of the car?
• A.

All that can be said is that the truck has more kinetic energy.

• B.

The truck has twice the kinetic energy of the car.

• C.

The truck has 4 times the kinetic energy of the car.

• D.

The truck has 8 times the kinetic energy of the car.

• 16.
Car J moves twice as fast as car K, and car J has half the mass of car K. The kinetic energy of car J, compared to car K is
• A.

The same.

• B.

2 to 1.

• C.

4 to 1.

• D.

1 to 2.

• 17.
An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy?
• A.

1/2

• B.

1/4

• C.

2

• D.

4

• 18.
A brick is moving at a speed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?
• A.

25 to 9

• B.

5 to 3

• C.

12.5 to 4.5

• D.

3 to 5

• 19.
A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?
• A.

The 4.0-kg mass

• B.

The 1.0-kg mass

• C.

Both travel the same distance.

• D.

Cannot be determined from the information given

• 20.
You slam on the brakes of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?
• A.

It would have skidded 4 times farther.

• B.

It would have skidded twice as far.

• C.

It would have skidded 1.4 times farther.

• D.

It is impossible to tell from the information given.

• 21.
A planet of constant mass orbits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic energy?
• A.

It remains constant.

• B.

It increases continually.

• C.

It decreases continually.

• D.

It increases when the planet approaches the Sun, and decreases when it moves farther away.

• 22.
The quantity mgy is
• A.

The kinetic energy of the object.

• B.

The gravitational potential energy of the object.

• C.

The work done on the object by the force.

• D.

The power supplied to the object by the force.

• 23.
The quantity 1/2 kx^2 is
• A.

The kinetic energy of the object.

• B.

The elastic potential energy of the object.

• C.

The work done on the object by the force.

• D.

The power supplied to the object by the force.

• 24.
Is it possible for a system to have negative potential energy?
• A.

Yes, as long as the total energy is positive.

• B.

Yes, since the choice of the zero of potential energy is arbitrary.

• C.

No, because the kinetic energy of a system must equal its potential energy.

• D.

No, because this would have no physical meaning.

• 25.
An object is released from rest a height h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second object compared to the first is
• A.

One-fourth as much.

• B.

One-half as much.

• C.

Twice as much.

• D.

Four times as much.

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