Chapter 4

Question 1

Acceleration is directly proportional to _

Answer 1

net force

Question 2

To increase the acceleration of an object…

Answer 2

increase the net force acting on it

Question 3

The Force of Friction…

Answer 3

Depends on the kinds of material and how much they are pressed together

Question 4

When Sanjay pushes a refrigerator across a kitchen floor at a constant speed, the force of friction between the refrigerator and the floor is
A. less than Sanjay’s push.
B. equal to Sanjay’s push.
C. equal and opposite to Sanjay’s push.
D. more than Sanjay’s push.

Answer 4

C. equal and opposite to Sanjay’s push.

Question 5

When Sanjay pushes a refrigerator across a kitchen floor
at an increasing speed, the amount of friction between
the refrigerator and the floor is
A. less than Sanjay’s push.
B. equal to Sanjay’s push.
C. equal and opposite to Sanjay’s push.
D. more than Sanjay’s push.

Answer 5

A. less than Sanjay’s push.

Question 6

What is mass?

Answer 6

The quantity of matter in an object.
It is also the measure of the inertia or
sluggishness that an object exhibits in
response to any effort made to start it,
stop it, or change its state of motion in any
way.

Question 7

What is weight?

Answer 7

Usually the force upon an object
due to gravity

Question 8

Mass (3-points)

Answer 8

• A measure of the inertia of a material object
• Independent of gravity: Greater inertia ⇒ greater
  mass
• Unit of measurement is the kilogram (kg)

Question 9

Weight (3-points)

Answer 9

• Usually the force on an object due to gravity
• Scientific unit of force is the newton (N)
• Unit is also the pound (lb)

Question 10

If the mass of an object is halved, the weight of the
object is
A. halved.
B. twice.
C. depends on location.
D. None of the above.

Answer 10

A. halved

Question 11

Weight and mass are __ proportional to each other.

Answer 11

directly

Question 12

When the string is pulled down slowly,
the top string breaks, which best
illustrates the
A. weight of the ball.
B. mass of the ball.
C. volume of the ball.
D. density of the ball.

Answer 12

A. weight of the ball.

Question 13

When the string is pulled down quickly, the bottom
string breaks, which best illustrates the
A. weight of the ball.
B. mass of the ball.
C. volume of the ball.
D. density of the ball.

Answer 13

B. mass of the ball.

Question 14

Acceleration in relation to mass (amount equation)

Answer 14

acceleration ~ 1/mass

Question 15

Acceleration is __ proportional to mass

Answer 15

inversely

Question 16

The same force applied to
* twice the mass produces __
* 3 times the mass, produces __

Answer 16

half the acceleration; 1/3 the acceleration.

Question 17

Newton’s second law (the law of
__) relates __.

Answer 17

acceleration; acceleration and force

Question 18

Newton’s second law

Answer 18

The acceleration produced by a net force
on an object is directly proportional to
the net force, is in the same direction as
the net force, and is inversely
proportional to the mass of the object

Question 19

Second law of motion equation

Answer 19

F=ma (Force=mass x acceleration)

Question 20

Newton’s second law acceleration equation

Answer 20

acceleration= net force/mass

Question 21

Remember the chart?

Answer 21

The brick scenario.

Question 22

Consider a cart pushed along a track with a certain
force. If the force remains the same while the mass
of the cart decreases to half, the acceleration of the
cart
A. remains relatively the same.
B. halves.
C. doubles.
D. changes unpredictably.

Answer 22

C. doubles.

Question 23

Push a cart along a track so twice as much net force
acts on it. If the acceleration remains the same,
what is a reasonable explanation?
A. The mass of the cart doubled when the force
doubled.
B. The cart experiences a force that it didn’t
before.
C. The track is not level.
D. Friction reversed direction.

Answer 23

A. The mass of the cart doubled when the force
doubled.

Question 24

The greater the mass of the object… (2-points)

Answer 24

greater its force of attraction toward the Earth and the smaller its tendency to move, that is, the greater its inertia.

Question 25

At one instant, an object in free fall has a speed of 40 m/s. Its speed 1 second later is A. also 40 m/s. B. 45 m/s. C. 50 m/s. D. None of the above.

Answer 25

C. 50 m/s.

Question 26

Gravitational Force=

Answer 26

10 m/s^2 (9.8)

Question 27

A 5-kg iron ball and a 10-kg iron ball are dropped from rest. For negligible air resistance, the acceleration of the heavier ball will be A. less. B. the same. C. more. D. undetermined.

Answer 27

B. the same.

Question 28

A 5-kg iron ball and a 10-kg iron ball are dropped from rest. When the free-falling 5-kg ball reaches a speed of 10 m/s, the speed of the free-falling 10-kg ball is A. less than 10 m/s. B. 10 m/s. C. more than 10 m/s. D. undetermined.

Answer 28

B. 10 m/s.

Question 29

When an object falls downward through the air it experiences... (2-points)

Answer 29

force of gravity pulling it downward; air drag force acting upward.

Question 30

The condition of nonfree fall... (2-points)

Answer 30

occurs when air resistance is nonnegligible; depends on two things: * speed and * frontal surface area.

Question 31

When the object is moving fast enough air resistance builds up to __.

Answer 31

equal the force of gravity

Question 32

When there is no net force from nonfree fall, that means that __. (2-points)

Answer 32

* No acceleration * Velocity does not change

Question 33

Terminal speed

Answer 33

occurs when acceleration terminates (when air resistance equals weight and net force is zero).

Question 34

Terminal velocity

Answer 34

same as terminal speed, with direction implied or specified

Question 35

When a 20-N falling object encounters 5 N of air resistance, its acceleration of fall is A. less than g. B. more than g. C. g. D. terminated.

Answer 35

A. less than g.

Question 36

If a 50-N person is to fall at terminal speed, the air resistance needed is A. less than 50 N. B. 50 N. C. more than 50 N. D. None of the above.

Answer 36

B. 50 N.

Question 37

As the skydiver falls faster and faster through the air, air resistance A. increases. B. decreases. C. remains the same. D. Not enough information.

Answer 37

A. increases.

Question 38

As the skydiver continues to fall faster and faster through the air, net force A. increases. B. decreases. C. remains the same. D. Not enough information.

Answer 38

B. decreases.

Question 39

As the skydiver continues to fall faster and faster through the air, her acceleration A. increases. B. decreases. C. remains the same. D. Not enough information.

Answer 39

B. decreases.

Question 40

Consider a heavy and a light person jumping together with same-size parachutes from the same altitude. Who will reach the ground first? A. The light person B. The heavy person C. Both will reach at the same time. D. Not enough information.

Answer 40

B. The heavy person

Question 41

When the air is removed by a vacuum pump and the coin and feather activity is repeated, A. the feather hits the bottom first, before the coin hits. B. the coin hits the bottom first, before the feather hits. C. both the coin and feather drop together side by side. D. Not enough information.

Answer 41

C. both the coin and feather drop together side by side.