# Chapter Test : Work, Energy And Power

50 Questions | Total Attempts: 1477  Settings  Questions pertain to the analysis of motion using relationships related to work and energy, mainly energy conservation and work-energy transfer principles. The following concepts are emphasized: work, positive work, negative work, energy, power, conservative (internal) forces, non-conservative (external) forces, potential energy, kinetic energy, mechanical energy, conservation of energy, work-energy theorem, pendulum, and incline planes.

• 1.
Which of the following statements are true about work?
• A.

Work is a form of energy.

• B.

A Watt is the standard metric unit of work.

• C.

Work is a time-based quantity; it is dependent upon how fast a force displaces an object.

• D.

None of the above.

• 2.
Which of the following statements are true about power?
• A.

Powerful people or powerful machines are simply people or machines which always do a lot of work.

• B.

Power refers to how fast work is done upon an object.

• C.

If person A and person B do the same job but person B does it faster, then person A does more work but person B has more power.

• D.

None of the above.

• 3.
Which of the following statements are true about conservative and non-conservative forces?
• A.

Physicists envy biologists' ability to instill order on the world of animal species through their taxonomic system. So physicists have made a habit of identifying forces as conservative and non-conservative forces in order to instill order on the world of forces.

• B.

A force is regarded as a non-conservative force if it does not add mechanical energy to a system of objects.

• C.

The force of gravity and elastic (spring) force are both examples of a conservative forces.

• D.

None of the above.

• 4.
Which of the following statements are true about kinetic energy?
• A.

If an object is on the ground, then it does not have any kinetic energy.

• B.

If an object is at rest, then it does not have any kinetic energy.

• C.

Kinetic energy is the form of mechanical energy which depends upon the position of an object.

• D.

None of the above.

• 5.
Which of the following statements are true about potential energy?
• A.

Moving objects cannot have potential energy.

• B.

Both gravitational and elastic potential energy are dependent upon the mass of an object.

• C.

Potential energy is the energy stored in an object due to its position.

• D.

None of the above.

• 6.
Which of the following statements are true about mechanical energy?
• A.

The total amount of mechanical energy of an object is the sum of its potential energy and the kinetic energy.

• B.

Heat is a form of mechanical energy.

• C.

The mechanical energy of an object is always conserved.

• D.

None of the above.

• 7.
A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in a auto service station. Lifting the more massive car requires ____ work. Presume that the value of g is ~10 m/s/s.
• A.

The same

• B.

Less

• C.

Twice as much

• D.

None of the above.

• 8.
An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. Whenreleased, the arrow will have a kinetic energy of ____ Joules. Presume that the value of g is ~10 m/s/s.
• A.

50

• B.

More than 50

• C.

Less than 50

• D.

None of the above.

• 9.
A child lifts a box up from the floor. The child then carries the box with constant speed to the other side of the room and puts the box down. How much work does he do on the box while walking across the floor at constant speed? Presume that the value of g is ~10 m/s/s.
• A.

Zero J

• B.

More than zero J

• C.

• D.

None of the above.

• 10.
A 1000-kg car is moving at 40.0 km/hr when the driver slams on the brakes and skids to a stop (with locked brakes) over a distance of 20.0 meters. How far will the car skid with locked brakes if it is traveling at 120. km/hr? Presume that the value of g is ~10 m/s/s.
• A.

20.0 m

• B.

60.0 m

• C.

180. m

• D.

None of the above.

• 11.
A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water. Presume that the value of g is ~10 m/s/s.
• A.

5000

• B.

500

• C.

10

• D.

None of the above.

• 12.
A ball is projected into the air with 100 J of kinetic energy. The kinetic energy is transformed into gravitational potential energy on the path towards the peak of its trajectory. When the ball returns to its original height, its kinetic energy is ____ Joules. Do consider the effects of air resistance. Presume that the value of g is ~10 m/s/s.
• A.

Less than 100

• B.

Not enough information given

• C.

More than 100

• D.

None of the above.

• 13.
During a construction project, a 2500 N object is lifted high above the ground. It is released and falls 10.0 meters and drives a post 0.100 m into the ground. The average impact force on the object is ____ Newtons. Presume that the value of g is ~10 m/s/s.
• A.

2500

• B.

25000

• C.

250,000

• D.

None of the above.

• 14.
A 10-Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ____ Joules. Presume that the value of g is ~10 m/s/s.
• A.

More than 10

• B.

0.5

• C.

10

• D.

None of the above.

• 15.
Luke Autbeloe stands on the edge of a roof throws a ball downward. It strikes the ground with 100 J of kinetic energy. Luke now throws another identical ball upward with the same initial speed, and this too falls to the ground. Neglecting air resistance, the second ball hits the ground with a kinetic energy of ____ J. Presume that the value of g is ~10 m/s/s.
• A.

Less than 100

• B.

100

• C.

More than 200

• D.

None of the above.

• 16.
An object at rest may have __________. Presume that the value of g is ~10 m/s/s.
• A.

Energy

• B.

Velocity

• C.

Acceleration

• D.

None of the above.

• 17.
A 50-kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ____ meters. Presume that the value of g is ~10 m/s/s.
• A.

5

• B.

10

• C.

50

• D.

None of the above.

• 18.
A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of ____, but different amounts of ____. Pick the two words which fill in the blanks in their respective order. Presume that the value of g is ~10 m/s/s.
• A.

Work, power

• B.

Force, work

• C.

Energy, work

• D.

None of the above.

• 19.
Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters? Presume that the value of g is ~10 m/s/s.
• A.

Lifting the 50 kg crate

• B.

Both require the same amount of work

• C.

Lifting the 25 kg crate

• D.

None of the above.

• 20.
A 50.0 kg crate is lifted to a height of 2.0 meters in the same time as a 25.0 kg crate is lifted to a height of 4 meters. The rate at which energy is used (i.e., power) in raising the 50.0 kg crate is ____ as the rate at which energy is used to lift the 25.0 kg crate. Presume that the value of g is ~10 m/s/s.
• A.

Twice as much

• B.

Half as much

• C.

The same

• D.

None of the above.

• 21.
Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building in 20.0 seconds. What power was required in this task?  Presume that the value of g is ~10 m/s/s.
• A.

20 W

• B.

100 W

• C.

50 W

• D.

None of the above.

• 22.
Approximate the work required lift a 2.5-kg object to a height of 6.0 meters.
• A.

~150 J

• B.

~250 J

• C.

~50 J

• D.

None of the above.

• 23.
A student applies a force to a cart to pull it up an inclined plane at a constant speed during a physics lab. A force of 20.8 N is applied parallel to the incline to lift a 3.00-kg loaded cart to a height of 0.450 m along an incline which is 0.636-m long. Determine the work done upon the cart and the subsequent potential energy change of the cart.
• A.

12 J

• B.

13.2 J

• C.

23.5 J

• D.

None of the above.

• 24.
Eddy, whose mass is 65.0-kg, climbs up the 1.60-meter high stairs in 1.20 s. Approximate Eddy's power rating.
• A.

P = 849 Watts

• B.

P = 749 Watts

• C.

P = 659 Watts

• D.

None of the above.

• 25.
A 65.8-kg skier accelerates down an icy hill from an original height of 521 meters. Use the work-energy theorem to determine the speed at the bottom of the hill if... (a) no energy is lost or gained due to friction, air resistance and other non-conservative forces.  (b) 1.40*105 J of energy are lost due to external forces.
• A.

(a) v = 101 m/s; (b) v = 77.2 m/s

• B.

(a) v = 77.2 m/s; (b) v = 101 m/s

• C.

(a) v = 151 m/s; (b) v = 87.2 m/s

• D.

None of the above.

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