AnswersDCSS Physics CR 24-25Unit Test

Unit Test — Unit test Answers

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The free-body diagrams of four objects are shown.

Question illustration
A
W
B
X
C
Y
D
Z
2
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A sports car and a minivan run out of gas and are pushed to the side of the road. Which is easier to push, and why?

A
the minivan, because it has more mass and therefore more inertia
B
the minivan, because it has less mass and therefore less inertia
C
the sports car, because it has more mass and therefore more inertia
D
the sports car, because it has less mass and therefore less inertia
3

Newton’s third law of motion says that for every action there is a(n) and opposite reaction.

Answer not available
4

According to Newton’s first law of motion, what will an object in motion do when no external force acts on it?

A
come to a stop
B
move at the same velocity
C
speed up
D
change direction
5

Two grocery carts have the same initial total momentum. The two carts collide, and now cart B has a greater final velocity.

A
It is less if cart B has a smaller mass.
B
It is greater if cart B has a greater mass.
C
It is the same if no external forces are added.
D
It depends on the masses of cart A and cart B.
6

[BLANK]

A
direction
B
magnitude
C
time
D
motion
7

Ingrid is participating in a relay race. While jogging at 9 km/h, she tosses a relay stick at 16 km/h to her teammate, who is standing still.

A
8 km/h
B
9 km/h
C
16 km/h
D
25 km/h
8

A boy and his skateboard have a combined mass of 65 kg. What is the speed of the boy and skateboard if they have a momentum of 275 kg • ?

Question illustration
A
0 m/s
B
0.24 m/s
C
4.2 m/s
D
8.5 m/s
9

Students are completing a lab in which they let a lab cart roll down a ramp. The students record the mass of the cart, the height of the ramp, and the velocity at the bottom of the ramp. The students then calculate the momentum of the cart at the bottom of the ramp.Which trial’s cart has the greatest momentum at the bottom of the ramp?

Question illustration
A
trial 1, because this trial has the greatest velocity
B
trial 2, because this trial has the greatest ramp height
C
trial 3, because this trial has a large mass and a large velocity
D
trial 4, because this trial has the greatest mass
10

How much force is needed to accelerate an object of mass 90 kg at a rate of 1.2 m/s2?

A
0.013 N
B
75 N
C
108 N
D
1080 N
11

A car’s momentum is p when it is traveling with a velocity of v. If the velocity of that car doubles, what is the new momentum of the car?

A
p
Option A
B
p
C
2p
D
4p
12

A train car has a mass of 10,000 kg and is moving at +3.0 m/s. It strikes an identical train car that is at rest. The train cars combine.

A
0 m/s
B
1.5 m/s
C
3.0 m/s
D
6.0 m/s
13

What best describes an impulse acting on an object?

A
the net force on an object divided by the time of impact
B
the velocity of an object divided by its mass
C
the product of an object's mass and the time of force impact
D
the product of an object's mass and its change in velocity
14

A velocity vs. time graph for an object is shown.

Question illustration
A
W and X
B
X and Y
C
Y and Z
D
W and Z
15

A baseball has a mass of 0.45 kg and is thrown with a speed of 25 m/s. What is the momentum of the baseball?

A
0.018 kg •
Option A
B
11 kg •
Option B
C
56 kg •
Option C
D
140 kg •
Option D
16

The weight of a bucket is 186 N. The bucket is being raised by two ropes. The free-body diagram shows the forces acting on the bucket. The acceleration of the bucket, to the nearest tenth, is m/s2.

Answer not available
17

The diagram shows a motion map for a train.

Question illustration
A
The train traveled south and then north.
B
The train moved at a velocity of 75 mph north.
C
The train had a greater velocity when it moved away from the origin.
D
The train stopped for 3 seconds.
18

Students perform an experiment in which they drop two eggs with equal mass from a balcony. In the first trial, the egg hits the ground and breaks. In the second trial, the egg hits a foam cushion and does not break or bounce.

A
The impulse was greater in the first experiment because the egg broke.
B
The impulse was greater in the second experiment because the egg did not break.
C
The impulse was the same in both experiments because the egg came to a stop.
D
The impulse cannot be determined without the mass and velocity of the eggs.
19

Which cars have the same magnitude of momentum? Check all that apply.

A
car 1
B
car 2
C
car 3
D
car 4
E
car 5
20

Which quantity may be calculated directly using Newton’s second law of motion?

A
weight
B
velocity
C
position
D
direction

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