Unit 3 Forces and Interactions

A train moves at a constant speed on a straight track. Which statement is true?

• No forces act on the train as it moves.

• The train accelerates

• the forces of the train's engine balance friction

• unbalanced forces keep the train moving

How could you accelerate if you were riding a bike?

• speeding up

• slowing down

• changing direction

• all are correct

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Two skaters stand on ice. One weighs 250 N, and the other weighs 500 N. They push against each other and move in opposite directions. Which one will travel farther before stopping?

• The skater weighing 250 N will move farther before stopping. Since it takes more force to push the heavier skater, the lighter skater will move farther with the given force.

• The skater weighing 250 N will move farther before stopping. Since it takes more force to push the lighter skater, the heavier skater will move farther with the given force.

• The skater weighing 500 N will move farther before stopping. Since it takes more force to push the heavier skater, the lighter skater will move farther with the given force.

• The skater weighing 500 N will move farther before stopping. Since it takes more force to push the lighter skater, the heavier skater will move farther with the given force.

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How does balanced forces affect objects that are moving and those that are not moving?

• Objects with balanced forces cause changes in motion in the direction of the greater force.

• Objects with balanced forces cause an object to keep moving.

• Objects with balanced forces is either not moving, or moving with constant velocity.

• Objects with balanced forces is moving with constant velocity.

How does unbalanced forces affect objects that are moving and those that are not moving?

• Objects with unbalanced forces cause changes in motion in the direction of the greater force.

• Objects with unbalanced forces cause an object to keep moving.

• Objects with balanced forces is either not moving, or moving with constant velocity.

• Objects with balanced forces is moving with constant velocity.

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How can the motion of runners throughout a race be described and compared?

• The runners will never accelerate.

• The runners will accelerate frequently throughout the race as their velocities change.

• The runners will have a constant speed.

• The runner’s velocity will never change.

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If the same force is applied to two objects, which will have the greater acceleration?

• The object with less mass

• The object with more mass

• The object with a rougher surface

• The object with more weight

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NGSS.MS-PS2-2

If the same force is applied to each of these balls, which will have the smallest acceleration?

• The baseball

• The golf ball

• The tennis ball

• The basketball

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Why is the acceleration in trial 2 greater than in trial 1?

• The distance is shorter

• The mass is greater

• The net force is greater

• The time is longer

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In which situation are the forces acting on a bicycle balanced?

• the bicycle speeds up as you pedal

• The speed of the bicycle is constant as it turns a corner

• The bicycle slows down as it coasts

• The bicycle moves in a straight line with constant speed as you pedal