Momentum — Unit test Answers

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A scientist on Earth drops a hammer and a feather at the same time an astronaut on the moon drops a hammer and a feather.

A
The hammer hits the ground before the feather on both Earth and the moon.
B
The hammer hits the ground before the feather on Earth, but the feather hits the ground first on the moon.
C
The hammer and the feather hit the ground together on both Earth and the moon.
D
The hammer hits the ground before the feather on Earth, and the hammer and feather hit at the same time on the moon.
3

A tugboat is pulling a barge into a harbor. The barge is exerting a force of 3000 N against the tugboat.Which force would most likely allow the tugboat to move the barge into the harbor?

A
4500 N in the opposite direction of the barge
B
3000 N in the opposite direction of the barge
C
3000 N in the same direction of the barge
D
4500 N in the same direction of the barge
4

best

H
His speed was 1 m/s, and his velocity was 0.
H
His speed was 2 m/s, and his velocity was 0.
H
His speed was 1 m/s, and his velocity was 1 m/s north.
H
His speed was 2 m/s, and his velocity was 2 m/s south.
5

Which example would most likely decrease friction?

A
using cleats, rather than gym shoes, on a field
B
using shaving cream, rather than shaving on dry skin
C
using a wide parachute, rather than a narrow parachute, when skydiving
D
using sandpaper, rather than regular paper, on wood
6

best

i
increasing the inertia of the car
d
decreasing the reaction force
i
increasing the action force
d
decreasing the mass of the car
7

The table represents the speed of a car in a northern direction over several seconds.

Question illustration
C
Column 1 should be titled “Time,” and Column 2 should be titled “Velocity.”
C
Column 1 should be titled “Velocity,” and Column 2 should be titled “Time.”
C
Column 1 should be titled “Time,” and Column 2 should be titled “Acceleration.”
C
Column 1 should be titled “Acceleration,” and Column 2 should be titled “Time.”
8

The information in the table represents the effect of the mass of two objects on the gravitational force between the two objects.Which number should be in the cell with the question mark?

Question illustration
A
The number is two because when you double the mass of one of the objects, the force between the objects is halved.
B
The number is four because when you double the mass of one of the objects, the force between the objects remains the same.
C
The number is eight because when you double the mass of one of the objects, the force between the objects also doubles.
D
The number is sixteen because when you double the mass of one of the objects, the force between the objects increases by a factor of 4.
9

Two objects collide and bounce apart. Assuming no outside forces act on the system, which best describes the total momentum after the collision?

A
It is always greater than it was before the collision.
B
It is often greater than it was before the collision.
C
It is always the same as it was before the collision.
D
It is often the same as it was before the collision.
11

Which describes an object’s speed when free falling in a vacuum?

A
The object accelerates until it reaches its terminal velocity.
B
The object falls at a constant speed because only one force acts on it.
C
The object falls faster and faster until it strikes the ground.
D
The object speeds up and then stops when air resistance equals gravity.
12

Riley is doing an experiment working with friction. He wants to find two ways to modify an object that could increase or decrease the same type of friction.

A
increasing roughness and speed
B
increasing surface area and aerodynamic design
C
using nonstick materials and ball bearings
D
using lubricants and increasing surface area

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