Free Printable Work, Energy and Power

1.

A force F at an angle θ above the horizontal is used to pull a heavy suitcase of weight mg a distance d along a level floor at constant velocity. The coefficient of friction between the floor and the suitcase is µ. The work done by the frictional force is:

a)

– µFdcosθ

b)

–Fdcosθ

c)

–µmgd

d)

–µmgdcosθ

2.

A 2 kg ball is attached to a 0.80 m string and whirled in a horizontal circle at a constant speed of 6 m/s. The work done on the ball during each revolution is:

a)

90J

b)

72J

c)

16J

d)

0

3.

A pendulum bob of mass m on a cord of length L is pulled sideways until the cord makes an angle θ with the vertical as shown in the figure to the right. The change in potential energy of the bob during the displacement is:

a)

mgL(1–cos θ)

b)

mgL(1–sin θ)

c)

mgLsinθ

d)

mgLcosθ

4.

A softball player catches a ball of mass m, which is moving towards her with horizontal speed V. While bringing the ball to rest, her hand moved back a distance d. Assuming constant deceleration, the horizontal force exerted on the ball by the hand is:

a)

$\frac{mv^2}{2d}$

b)

$\frac{mv^2}{d}$

c)

$\frac{2mv}{d}$

d)

$\frac{mv}{d}$

5.

A pendulum is pulled to one side and released. It swings freely to the opposite side and stops. Which of the following might best represent graphs of kinetic energy (E_k), potential energy (E_p) and total mechanical energy (E_T)?

a)

A

b)

B

c)

C

d)

D

6.

A car of mass m slides across a patch of ice at a speed v with its brakes locked. It the hits dry pavement and skids to a stop in a distance d. The coefficient of kinetic friction between the tires and the dry road is µ. If the car has a mass of 2m, it would have skidded a distance of:

a)

0.5d

b)

d

c)

1.41d

d)

2d

7.

A car of mass m slides across a patch of ice at a speed v with its brakes locked. It the hits dry pavement and skids to a stop in a distance d. The coefficient of kinetic friction between the tires and the dry road is µ. If the car has a speed of 2v, it would have skidded a distance of:

a)

4d

b)

d

c)

1.41d

d)

2d

8.

A football is kicked off the ground a distance of 50 yards downfield. Neglecting air resistance, which of the following statements would be INCORRECT when the football reaches the highest point?

a)

All of the balls original kinetic energy has been changed into potential energy.

b)

The ball’s horizontal velocity is the same as when it left the kickers foot.

c)

The ball will have been in the air one-half of its total flight time.

d)

The vertical component of the velocity is equal to zero.

9.

A fan blows the air and gives it kinetic energy. An hour after the fan has been turned off, what has happened to the kinetic energy of the air?

a)

It disappears.

b)

It turns into potential energy.

c)

It turns into thermal energy.

d)

It turns into sound energy.

10.

From the top of a high cliff, a ball is thrown horizontally with initial speed v_o. Which of the following graphs best represents the ball's kinetic energy K as a function of time t?

a)

D

b)

A

c)

B

d)

C

11.

The figure shows a rough semicircular track whose

ends are at a vertical height h. A block placed at

point P at one end of the track is released from rest

and slides past the bottom of the track. Which of the

following is true of the height to which the block

rises on the other side of the track?

a)

It is equal to $\frac{h}{2\pi}$

b)

It is equal to $\frac{h}{4}$

c)

It is equal to $\frac{h}{2}$

d)

It is equal to $h$

e)

It is between zero and h; the exact height depends on how much energy is lost to friction.

12.

A block of mass m slides on a horizontal frictionless table with an initial speed v_o. It then compresses a spring. How much is the spring compressed from its natural length?

a)

$\frac{v_0^2}{2g}$

b)

$v_0\ \frac{mg}{k}$

c)

$v_0\ \frac{m}{k}$

d)

$v_0\sqrt{\frac{m}{k}}$

e)

$v_0\sqrt{\frac{k}{m}}$

13.

From the top of a 70-meter-high building, a l-kilogram ball is thrown directly downward with an initial speed of 10 meters per second. If the ball reaches the ground with a speed of 30 meters per second, the energy lost to friction is most nearly:

a)

0J

b)

100J

c)

300J

d)

400J

e)

700J

14.

What happen to the gravitational force on a body when you move away from earth's surface?

a)

It decreases

b)

It increases

c)

It stays constant

d)

It is converted into kinetic energy

15.

A frictionless pendulum of length 3 m swings with an amplitude of 10°. At its maximum displacement, the potential energy of the pendulum is 10 J. What is the kinetic energy of the pendulum when its potential energy is 5 J ?

a)

3.3 J

b)

5 J

c)

6.7 J

d)

10 J

e)

15 J

Work, Energy and Power

Total questions: 15

Worksheet time: 13mins

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