Changes in Motion and Force Unit Review

CHOOSE THE BEST ANSWER RESPONSE THAT INCLUDES CONTENT FROM EVERYTHING YOU'VE LEARNED IN THIS UNIT:

In a warehouse, the workers sometimes slide boxes along the floor to move them. Two boxes were sliding toward each other and crashed. The crash caused both boxes to change speed. Based on the information in the diagram, which statement is correct? In your answer, explain what the forces were like and why the boxes changed speed.

• When the boxes crashed, they changed motion because they both experienced a force that was opposite to their direction of motion. I know this because Box 1 reversed direction and Box 2 slowed down. Both of these changes in motion are caused by forces that are opposite to the direction the object is moving.

• When the boxes crashed, they changed motion because they both experienced a force that was opposite to their direction of motion. I know this because Box 1 reversed direction and Box 2 slowed down. Both of these changes in motion are caused by forces that are opposite to the direction the object is moving. I know that the more massive an object is, the less it changes motion from a given force, but there is no information about the force strength on these objects, so I don't know the mass of the box.

• Box 1 has more mass than Box 2. I know this because when the two boxes crashed, they experienced the same strength force in opposite directions. Since Box 1 had less change in speed from this force, it must have more mass than Box 2. That's because when the same strength force is exerted on objects of different mass, the less massive object will have a greater change in velocity.

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In which crash did the tennis ball experience a stronger force? How do you know?

• Crash 1; the force on the soccer ball was stronger in this crash, so the force on the tennis ball was also stronger.

• There was no force on the tennis ball. In each crash only on the soccer ball experienced a force.

• It was the same in both crashes. The soccer ball changed speed by the same amount in each crash, so the force on the tennis ball was the same both times.

• The diagram doesn’t tell you anything about the force on the tennis ball. It only gives information about the force on the soccer balls.

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Three people can move a piano easier than two people. This demonstrates which of Newton's Laws of Motion?

• Newton's 1st Law (Inertia)

• Newton's 2nd Law (F= m x a)

• Newton's 3rd Law (Action Forces & Reaction Forces)

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Which of the following graphs shows how the mass of an object affects the amount of force needed to move it?

• B

• A

• C

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A diagram of forces being applied to a box by four people is illustrated below. If the net force acting on the box is 10 N to the right, what is the magnitude of the force applied by the boy pulling to the left?

• 14N

• 21N

• 19N

• 11N

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Which Law of Motion says that force equals mass times acceleration?

• Newton's 2nd law

• Newton's 3rd law

• Newton's 1st law

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For every action force, there is a reaction force equal in strength opposite in direction.

• Newton's 3rd law

• Newton's 4th law

• Newton's 2nd law

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If you increase the force on an object, its acceleration? 

• decreases

• stays the same

• also increases

• stops

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If two forces act on an object in the same direction, the net force is the _____________

• the difference between the two forces

• the sum of the two forces

• Only one of the forces acts on the object

• DOOMSDAY!

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What is the net force?

• 10 N

• 0 N

• 25 N

• 1 N

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