Physics MCQS

 1. Which of the following is NOT a correct unit for work?

A. erg

B. ft·lb

C. watt

D. newton·meter

E. joule

ans: C

2. Which of the following groups does NOT contain a scalar quantity?

A. velocity, force, power

B. displacement, acceleration, force

C. acceleration, speed, work

D. energy, work, distance

E. pressure, weight, time

ans: B

3. A boy holds a 40-N weight at arm’s length for 10 s. His arm is 1.5 m above the ground. The

work done by the force of the boy on the weight while he is holding it is:

A. 0

B. 6.1 J

C. 40 J

D. 60 J

E. 90 J

ans: A

4. An object moves in a circle at constant speed. The work done by the centripetal force is zero

because:

A. the displacement for each revolution is zero

B. the average force for each revolution is zero

C. there is no friction

D. the magnitude of the acceleration is zero

E. the centripetal force is perpendicular to the velocity

ans: E

5. An object of mass 1 g is whirled in a horizontal circle of radius 0.5 m at a constant speed of

2 m/s. The work done on the object during one revolution is:

A. 0

B. 1 J

C. 2 J

D. 4 J

E. 16 J

ans: A

6.. The work done by gravity during the descent of a projectile:

A. is positive

B. is negative

C. is zero

D. depends for its sign on the direction of the y axis

E. depends for its sign on the direction of both the x and y axes

ans: A

7. A baseball is hit high into the upper bleachers of left field. Over its entire flight the work done

by gravity and the work done by air resistance, respectively, are:

A. positive; positive

B. positive; negative

C. negative; positive

D. negative; negative

E. unknown since vital information is lacking

ans: D

8. A line drive to the shortstop is caught at the same height as it was originally hit. Over its

entire flight the work done by gravity and the work done by air resistance, respectively, are:

A. zero; positive

B. zero; negative

C. positive; negative

D. negative; positive

E. negative; negative

ans: B
9. A 2-kg object is moving at 3 m/s. A 4-N force is applied in the direction of motion and then

removed after the object has traveled an additional 5 m. The work done by this force is:

A. 12 J

B. 15 J

C. 18 J

D. 20 J

E. 38 J

ans: D

10. A sledge (including load) weighs 5000 N. It is pulled on level snow by a dog team exerting a

horizontal force on it. The coefficient of kinetic friction between sledge and snow is 0.05. How

much work is done by the dog team pulling the sledge 1000 m at constant speed?

A. 2.5 × 104 J

B. 2.5 × 105 J

C. 5.0 × 105 J

D. 2.5 × 106 J

E. 5.0 × 106 J

ans: B

11. Camping equipment weighing 6000 N is pulled across a frozen lake by means of a horizontal

rope. The coefficient of kinetic friction is 0.05. The work done by the campers in pulling the

equipment 1000 m at constant velocity is:

A. 3.1 × 104 J

B. 1.5 × 105 J

C. 3.0 × 105 J

D. 2.9 × 106 J

E. 6.0 × 106 J

ans: C

12. Camping equipment weighing 6000 N is pulled across a frozen lake by means of a horizontal

rope. The coefficient of kinetic friction is 0.05. How much work is done by the campers in

pulling the equipment 1000 m if its speed is increasing at the constant rate of 0.20 m/s

2

?

A. −1.2 × 106 J

B. 1.8 × 105 J

C. 3.0 × 105 J

D. 4.2 × 105 J

E. 1.2 × 106 J

ans: D

13.. A 1-kg block is lifted vertically 1 m by a boy. The work done by the boy is about:

A. 1 ft · lb

B. 1 J

C. 10 J

D. 0.1 J

E. zero

ans: C

14.. An 80-N crate slides with constant speed a distance of 5.0 m downward along a rough slope

that makes an angle of 30◦ with the horizontal. The work done by the force of gravity is:

A. −400 J

B. −200 J

C. −69 J

D. 200 J

E. 400 J

ans: D

15. A man pulls a sled along a rough horizontal surface by applying a constant force Fn at an angle

θ above the horizontal. In pulling the sled a horizontal distance d, the work done by the man

is:

A. F d

B. F d cos θ

C. F d sin θ

D. F d/ cos θ

E. F d/ sin θ

ans: B

16. A man wishes to pull a crate 15 m across a rough floor by exerting a force of 100 N. The

coefficient of kinetic friction is 0.25. For the man to do the least work, the angle between the

force and the horizontal should be:

A. 0

B. 14◦

C. 43◦

D. 66◦

E. 76◦

ans: A

17. A particle moves 5 m in the positive x direction while being acted upon by a constant force

Fn = (4 N)ˆi + (2 N)ˆj − (4 N)ˆ

k. The work done on the particle by this force is:

A. 20 J

B. 10 J

C. −20 J

D. 30 J

E. is impossible to calculate without knowing other forces

ans: A

18. A block is attached to the end of an ideal spring and moved from coordinate xi to coordinate

xf . The relaxed position is at x = 0. The work done by spring is positive if:

A. xi = 2 cm and xf = 4 cm

B. xi = −2 cm and xf = 4 cm

C. xi = −2 cm and xf = −4 cm

D. xi = 2 cm and xf = −4 cm

E. xi = −4 cm and xf = −2 cm

ans: E

19. When a certain rubber band is stretched a distance x, it exerts a restoring force of magnitude

F = Ax, where A is a constant. The work done by a person in stretching this rubber band

from x = 0 to x = L, beginning and ending at rest, is:

A. AL2

B. A + 2L

C. A + 2L2

D. A/L

E. AL2/2

ans: E

20. When a certain rubber band is stretched a distance x, it exerts a restoring force of magnitude

F = ax+bx2, where a and b are constants. The work done in stretching this rubber band from

x = 0 to x = L is:

A. aL2 + bLx3

B. aL + 2bL2

C. a + 2bL

D. bL

E. aL2/2 + bL3/3

ans: E

21. An ideal spring is hung vertically from the ceiling. When a 2.0-kg mass hangs at rest from it

the spring is extended 6.0 cm from its relaxed length. A downward external force is now applied

to the mass to extend the spring an additional 10 cm. While the spring is being extended by

the force, the work done by the spring is:

A. −3.6 J

B. −3.3 J

C. −3.4 × 10−5 J

D. 3.3 J

E. 3.6 J

ans: A

22. An ideal spring is hung vertically from the ceiling. When a 2.0-kg block hangs at rest from it

the spring is extended 6.0 cm from its relaxed length. A upward external force is then applied

to the block to move it upward a distance of 16 cm. While the block is moving upward the

work done by the spring is:

A. −1.0 J

B. −0.52 J

C. −0.26 J

D. 0.52 J

E. 1.0 J

ans: A