Exam 2

Question 1

Work is a vector. True of False?

Answer 1

true

Question 2

In which circumstance is work not zero?
A. The net force is perpendicular to the displacement.
B. There is no net displacement.
C. The motion is uniform and circular.
D. The kinetic energy changes.

Answer 2

d

Question 3

To stretch a spring twice as far requires
A. double the work.
B. four times the work.
C. sixteen times the work.
D. half the work.

Answer 3

a

Question 4

If the kinetic energy is decreasing, the force
A. is perpendicular.
B. opposes the motion.
C. is aligned with the motion.
D. is zero.

Answer 4

b.

Question 5

The SI unit for energy, the joule, is
A. kg m/s
B. kg m/s2
C. kg m2/s2
D. kg m2/s

Answer 5

c

Question 6

A force is conservative if
A. the work is independent of the path.
B. the total energy is conserved.
C. the work done on any closed path is zero.
D. all the above.

Answer 6

a

Question 7

At a turning point
A. the force goes to zero.
B. the speed goes to zero.
C. the potential energy goes to zero.
D. none of these.

Answer 7

b

Question 8

At an equilibrium point
A. the force goes to zero.
B. the speed goes to zero.
C. the potential energy goes to zero.
D. none of these.

Answer 8

a

Question 9

For an orbit about the Earth, the closest and farthest points are
A. the apogee and perigee.
B. the perigee and apogee.
C. the perihelion and aphelion.
D. the aphelion and perihelion.

Answer 9

b. perigee is closest, apogee is farthest

Question 10

The escape speed
A. provides enough kinetic energy to break free of a planet’s gravity.
B. is the speed of light at the event horizon of a black hole.
C. is computed without taking drag forces into account.
D. all of these.

Answer 10

d

Question 11

All phenomenological forces are conservative.
T. true.
F. false.

Answer 11

false

Question 12

Energy is conserved if
A. all forces in the system are conservative.
B. nonconservative forces are perpendicular to
displacements.
C. nonconservative forces do no work.
D. all the above.

Answer 12

d

Question 13

In Newton’s second law for rotation τ = Iα, I plays the role
of mass. This quantity is
A. the impulse.
B. the current.
C. the moment of inertia.
D. none of these.

Answer 13

c. the moment of inertia

Question 14

A kilowatt-hour is a unit of
A. power.
B. force.
C. energy.
D. electricity.

Answer 14

a

Question 15

Arc length is
A. a fraction of the circumference of a circle.
B. the radius times the angular displacement.
C. both.
D. neither.

Answer 15

c.both

Question 16

The moment of inertia of an object depends upon
A. its mass.
B. the axis of rotation.
C. the distribution of the mass.
D. all of these.

Answer 16

d. all

Question 17

If the moment of inertia is computed by summing the
moments of different parts, the axis chosen for each part
does not matter.
T. true.
F. false.

Answer 17

false

Question 18

A hoop and disk of the same radius and same mass start
from rest at the same point on an incline. Which reaches
the bottom of the incline first?
A. The hoop.
B. The disk.
C. It’s a tie.

Answer 18

b

Question 19

For the impulse approximation, external forces are ignored
because
A. they don’t exist.
B. they are small compared to the internal forces of the
collision.
C. they are large but perpendicular to the momentum.
D. none of these.

Answer 19

b

Question 20

Momentum is conserved during any collision, but energy is
conserved only for
A. perfectly inelastic collisions.
B. inelastic collisions.
C. elastic collisions.
D. none of these.

Answer 20

c

Question 21

The greater the damping, the quicker the system comes to
rest.
T. true.
F. false.

Answer 21

false

Question 22

Oscillations occur for which case?
A. underdamped
B. critically damped
C. overdamped
D. both A and B

Answer 22

a

Question 23

A forced and damped oscillator will eventually oscillate at
A. its natural frequency
B. the forcing frequency
C. an average of the two
D. it comes to a halt instead of continuing to oscillate

Answer 23

b

Question 24

A force can be adjusted to be in resonance with an
oscillatory system by
A. increasing the strength
B. decreasing the strength
C. adjusting the frequency
D. a lucky guess

Answer 24

c

Question 25

``` Stress is A. force per unit area B. a measure of deformation C. tension D. anxiety producing ```

Answer 25

a

Question 26

A point on a body rotating about a fixed axis with nonzero angular acceleration executes uniform circular motion. T. true. F. false

Answer 26

true

Question 27

``` To have the smallest linear speed while standing on or near the surface of the rotating Earth, you should be at A. the equator. B. one of the poles. C. the bottom of the deepest gold mine. D. the peak of the tallest mountain. ```

Answer 27

b

Question 28

Suppose a wheel is rolling and slipping on a rough surface in such a way that the tangential speed is greater than the linear speed of the axis. A. friction will reduce the linear speed. B. friction will reduce the tangential speed. C. friction will reduce both. D. friction will reduce neither.

Answer 28

c

Question 29

A torque is independent of the choice of axis. T. true. F. false.

Answer 29

false

Question 30

Net torque due to a couple is independent of the choice of axis. T. true. F. false.

Answer 30

true

Question 31

The velocity of a string passing over a pulley without slipping is A. the same as the angular velocity of the pulley. B. the same as the tangential velocity of the rim of the pulley. C. unrelated to the rotation of the pulley. D. none of these.

Answer 31

b

Question 32

In simple harmonic motion, the largest positive acceleration occurs when A. when the displacement is largest and positive. B. when the displacement is zero. C. when the displacement is largest and negative. D. none of these.

Answer 32

c

Question 33

In simple harmonic motion, the largest positive velocity occurs when A. when the displacement is largest and positive. B. when the displacement is zero. C. when the displacement is largest and negative. D. none of these.

Answer 33

b

Question 34

``` Frequency is A. the time for one cycle. B. the angular frequency. C. the number of cycles per unit time. D. none of these. ```

Answer 34

c

Question 35

To increase the frequency of oscillations for a mass on a spring, you should A. increase the mass and increase the spring constant. B. decrease the mass and increase the spring constant. C. increase the mass and decrease the spring constant. D. decrease the mass and decrease the spring constant.

Answer 35

b

Question 36

If the amplitude of oscillation is increased by a factor of two, A. the maximum velocity increases by two and the energy by two. B. the maximum velocity increases by four and the energy by two. C. the maximum velocity increases by two and the energy by four. D. the maximum velocity increases by four and the energy by four.

Answer 36

c

Question 37

``` The period of a pendulum is independent of the amplitude if A. the pendulum is short. B. the pendulum is light. C. the pendulum angle is small. D. none of these. ```

Answer 37

c

Question 38

Energy is not conserved if A. nonconservative forces do work. B. not all of the motion is taken into account. C. an external system interacts with the system of interest. D. all the above.

Answer 38

d

Question 39

``` Strain is A. force per unit area B. a measure of deformation C. tension D. debilitating ```

Answer 39

b

Question 40

Hooke’s law is equivalent to stress and strain being proportional. T. true F. false

Answer 40

true