Work/Energy

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book cover
Holt Physics
Chapter 5
Grade levels:
11th grade, 12th grade
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1

A centripetal force does no work because
a. the motion is curved
b. there is no acceleration
c. the force is parallel to the motion
d. the force is perpendicular to the motion

d. the force is perpendicular to the motion

2

A box is pulled across a table at a constant speed by a horizontal force parallel to the table in the direction of motion. A force performing no work during the motion is
a. the applied force
b. the friction force
c. the normal force of the table on the block
d. all the above forces do work during the motion

c. the normal force of the table on the box

3

Which of the following must be true of a conservative force?
a. The energy always increases when the force acts
b. The energy always decreases when the force acts
c. The potential energy may either increase or
decrease when the force acts
d. the potential energy is a constant of the
motion
e. the kinetic energy is a constant of the motion.

c. The potential energy may either increase or decrease when the force acts.

4

A force does work on an object if a component of the force
a. is perpendicular to the displacement of the
object
b. is parallel to the displacement of the object
c. perpendicular to the displacement of the object
moves the object along a path that returns the
object to its starting position
d. parallel to the displacement of the object
moves the object along a path that returns the
object to its starting position

b. is parallel to the displacement of the object

5

Work is done when
a. the displacement is not zero
b. the displacement is zero
c. the force is zero
d. the force and displacement are perpendicular

a. the displacement is not zero

6

If the only force acting on an object is friction during a given physical process, which of the following assumptions must be made in regard to the objects kinetic energy?
a. The kinetic energy increases
b. The kinetic energy decreases
c. The kinetic energy remains constant
d. The kinetic energy decreases than increases

b. the kinetic energy decreases.

7

The main difference between kinetic energy and potential energy is that
a. kinetic energy involves position and potential
energy involves motion
b. kinetic energy involves motion and potential
energy involves position
c. although both energies involve motion, only
kinetic involves position
d. although both energies involve position, only
potential involves motion

b. kinetic energy involves motion and potential energy involves position

8

The equation for determining gravitational potential energy is PE = mgh. Which factor(s)in this equation is(are) not a property of the object?
a. g
b. h
c. m
d. both g and h

d. both g and h

9

In the presence of frictional force,
a. non-mechanical energy is negligible, and
mechanical energy is no longer conserved
b. non-mechanical energy is negligible and
mechanical energy is conserved
c. non-mechanical energy is no longer negligible
and mechanical energy is conserved
d. non-mechanical energy is no longer negligible
and mechanical energy is not conserved.

d. non-mechanical energy is no longer negligible and mechanical energy is not conserved.

10

Why doesn't the principle of mechanical energy conservation hold in situations when frictional forces are present?
a. kinetic energy is not simply converted to a
form of potential energy
b. potential energy is simply converted to a form
of gravitational energy
c. chemical energy is not simple converted to
electrical energy
d. kinetic energy is simply converted to a form
of gravitational energy

a. kinetic energy is not simply converted to a form of potential energy

11

Which of the following are examples of conservable quantities?
a. potential energy and length
b. mechanical energy and length
c. mechanical energy and mass
d. kinetic energy and mass

c. mechanical energy and mass

12

Each of five satellites makes a circular orbit about an object that is much more massive than any of the satellites. The mass and orbital radius of each satellite is given below. Which satellite has the greatest speed?
Mass radius
a. 1/2 m R
b. m 1/2 R
c. m R
d. m 2R
e. 2m R

b. mass = m, radius = 1/2 R

13

Two planets have the same size, but different masses, and no atmosphere. Which of the following would be the same for objects with equal mass on the surface of the two planets.
I. The rate at which each would fall freely
II. The amount of mass each would balance on
equal arm balance
III. The amount of momentum each would aquire
when given a certain impulse

a. I only
b. III only
c. I and II only
d. II and III only
e. I, II, and III

d. II and III only

14

A person weighing 800 Newtons on Earth travels to another planet with twice the mass and twice the radius of Earth. The person's weight on this other planet is most nearly
a. 1600 N
b. 800 /2 N
c. 800 N
d. 400 N

d. 400 N

15

Which of the following quantities is a scalar that is always positive or zero?
a. Power
b. Work
c. Kinetic energy
d. Linear momentum

c. Kinetic energy

16

A rock is lifted for a certain time by a force F that is greater in magnitude than the rock's weight W. The change in kinetic energy of the rock during this time is equal to the
a. Work done by F
b. Work done by W
c. Work done by (F - W)
d. difference in the potential energy of the rock
before and after this time

c. work done by (F - W)

17

Two artificial satellites, A and B, orbit the earth with radii of R and 2R respectively. What is the relationship between the accelerations of A and B.
a. a(B) = 4a(A)
b. a(B) = 2a(A)
c. a(B) = a(A)
d. a(B) = 1/2 a(A)
e. a(B) = 1/4 a(A)

e. a(B) = 1/4 a(A)