Forces and Changes in Motion

If all the forces acting upon an object at rest are balanced, what will the object do?

• The object will stay still

• The object will slow down

• The object will accelerate

• The object will change position

Something that makes an object start moving, stop moving, speed up, or slow down is a(n) .

• load

• position

• effort

• force

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NGSS.MS-PS2-2

The tendency of an object to stay in motion or at rest until a force acts upon it is

• inertia

• gravity

• speed

• frame of reference

A child rides a wagon down a hill. Eventually, the wagon comes to a stop. Which is most responsible for causing the wagon to stop?

• gravity acting on the wagon

• the mass of the wagon

• friction acting on the wagon

• the mass of the child

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NGSS.MS-PS2-2

A pencil falls off of a desk. What moves the pencil toward the floor? 

• mass

• friction

• gravity

• speed

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NGSS.MS-PS2-4

Four solid balls, each with a different mass, are moving at the same speed. Which ball would require the most force to stop its motion? 

• ball with a mass of 5 kg 

• ball with a mass of 10 kg 

• ball with a mass of 15 kg 

• ball with a mass of 20 kg

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NGSS.MS-PS2-2

What can cause a moving object to increase its speed in a forward direction? 

• a force pushing on the object from the opposite direction 

• a force that continually acts on the object in the direction the object is moving 

• an increase in the mass of the object 

• a decrease in the mass of the object 

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NGSS.HS-PS2-1

Which best describes the role friction plays in the operation of a car?

• Friction makes a car go faster.

• Friction keeps a car from stopping.

• Friction turns the car in a new direction.

• Friction helps a car slow down and stop.

Rosa tried to pound a large nail into a board using a small hammer. Partway into the board, the nail stopped and would not move when she hit it. Rosa switched to using a heavier hammer, and the nail went into the board easily. Why did the larger hammer work when the small hammer did not?

• The nail could not push the larger hammer out of the way.

• There is more friction between a large hammer and the nail.

• The flat part of the larger hammer was wider, so it hit the nail better.

• The larger hammer had more mass, so it exerted more force when it hit the nail.

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NGSS.MS-PS2-2

Suri places magnets on three identical toy cars to give them different masses. Then, Suri measures how far each car rolls when she launches it from the same starting point using the same stretched rubber band. The three toy cars are pictured in the following illustration. How will the force of the rubber band affect the cars?

• Car 3 will travel the longest distance.

• Car 1 will travel the shortest distance.

• Car 3 will have the least change in its motion.

• Car 1 will have the greatest change in its motion.

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NGSS.MS-PS2-1

NGSS.MS-PS2-2