3.3 - Using Newton's Laws(30pts.)

When a falling object reaches terminal velocity, the force of gravity _____ the force of air resistance.

• is related to

• is greater than

• is less than

• is equal to

Answer explanation

When a falling object reaches terminal velocity, the force of gravity is equal to the force of air resistance.

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HS-PS2-2

When an object moves in a circular path, the net force is called a(n) (a)   ​ (b)   .

• centripetal

• force

• centrifugal

• velocity

• speed

• momentum

Answer explanation

When an object moves in a circular path, the net force is called a centripetal force, which acts towards the center of the circle to keep the object in its path.

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HS-PS2-2

Describe what happens to the momentum of two billiard balls that collide.

• If there are no outside forces, the momentum of two colliding billiard balls is the same before and after the collision.

• If there are no outside forces, the momentum of the 8-ball is the greatest because you have to make that one last.

• If there are no outside forces, the forces cancel and the balls stop.

• If there are no outside forces, the velocities will both be in the same direction.

Answer explanation

If there are no outside forces, the momentum of two colliding billiard balls is the same before and after the collision.

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HS-PS2-2

When a rocket lifts off, its upward momentum is matched by the downward momentum of _____.

• nothing

• hot gases expelled by the rocket

• air pushed out of the way by the rocket

• the launch pad

Answer explanation

When a rocket lifts off, its upward momentum is matched by the downward momentum of hot gases expelled by the rocket.

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HS-PS2-2

What principle explains the behavior of a balloon that is released before being tied and flies around the room?

• Newton's First Law of Motion

• Newton's Second Law of Motion

• Newton's Third Law of Motion

• Conservation of Energy

Answer explanation

The behavior of the balloon can be explained by Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When the balloon is released, the air escaping propels it in the opposite direction.

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HS-PS2-2

On the Moon (with no Air), if a feather and a hammer are dropped at the same time from the same height, what will happen?

• The feather will hit the ground first

• The hammer will hit the ground first

• They will hit the ground at the same time

• They will float indefinitely

Answer explanation

In the absence of air resistance on the Moon, both the feather and the hammer will fall at the same rate due to gravity, causing them to hit the ground simultaneously.

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HS-PS2-2

Suppose you are standing on a scale in an elevator that is accelerating upward.

Will the scale read your weight as larger or smaller than the weight it reads when you are stationary?

Explain.

• Larger, the force that the scale exerts on you is greater than your weight; the reading would increase.

• Larger, The force that the scale exerts on you is less than your weight; the reading would decrease.

• Smaller, The force that the scale exerts on you is less than your weight; the reading would increase.

• Smaller, The force that the scale exerts on you is greater than your weight; the reading would decrease.

Answer explanation

Larger, the force that the scale exerts on you is greater than your weight; the reading would increase.

Tags

HS-PS2-1

Use the following terms to complete the concept map on forces:

b

a

c

d

e

Distance

Mass

Friction

Speed

Air Resistance

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HS-PS2-1

Forces that cancel each other are called ​ (a)   forces.

• balanced

• inactive

• neutral

• null

• unbalanced

Answer explanation

Balanced forces cancel each other out, resulting in no net force. This equilibrium is essential in understanding the dynamics of objects.

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HS-PS2-2

Slamming on the brakes in a moving car makes a passenger move forward against his or her seat belt because

• the passenger has the inertia to keep moving forward

• the passenger is being pushed by the seats of the car

• the passenger is better able to stop themselves in this manner

• the passenger has an equal and opposite force supporting their weight

Answer explanation

The passenger has the inertia to keep moving forward, as per Newton's first law of motion.

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HS-PS2-2