Forces and Changes in Motion Study Guide

Carlos uses one golf ball to set another golf ball in motion. The following diagram shows how Carlos designs his experiment. Carlos releases the ball on the string from different heights. Each time, the first ball strikes the second ball, which then rolls down the track. Which force causes the first ball to swing

downward?

• a pull due to gravity

• a pull from the string

• a push from Carlos’s hand

• friction between air and the golf ball

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Mindy wants to find out the average distance that each of her six friends can throw a ball.

She asks six friends of similar sizes and ages to throw a ball as far as possible from the

same starting point. Mindy notices that one friend throws the ball much farther than the

other five do. She wants her results to be accurate. What should Mindy do?

• Repeat the experiment for the person with the unusual result.

• Repeat the experiment using a different friend as a replacement.

• Repeat the experiment and ignore the results of the first experiment.

• Repeat the experiment two more times, and find averages for each of the six

  throwers.

Bobby draws pictures to show how force and motion are involved in his daily activities.

Which drawing shows Bobby using a pulling force to affect motion?

• 
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• 
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Jane likes to play many types of sports. During the course of a week, she goes bowling

and plays soccer, baseball, and volleyball. Jane thinks the bowling ball requires the most

force to move. Why would it require the most force?

• It has the most mass.

• She has to throw it indoors.

• She has to hold it in her hand.

• It is all black and the other balls have white on them.

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The amount of friction exerted when an object moves across a surface depends on

how the object and the surface rub together. For which of these surfaces will friction be

greatest when a block of wood slides across it?

• wet ice

• glass mirror

• thick carpet

• waxed wood

Mary Lou is pushing her younger brother, Steve, in his toy car. Steve gets out of the car.

Steve's friend, who has more mass than he does, gets into the car. If Mary Lou wants to

make the car go the same distance that it did when she pushed Steve, what should she

do?

• Push the car with less force.

• Push the car with more force.

• Push the car with the same amount of force.

• Add more mass to the car and push it with the same amount of force.

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This spring scale is measuring the force on a block hanging from the hook. What would be

the reading on the scale if an identical second block were added?

• 2.2 N

• 2.2 g

• 4.4 N

• 4.4 g

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Lin-Yuan placed each of the objects on a smooth surface. He then used a spring device

that applied 10 N of force to each object. Assume that the friction experienced by each

object is the same. Which object traveled farthest?

• metal washer

• plastic disk

• rock

• wooden block

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A rock is balanced on the side of a hill. Although the rock is heavy, a gentle push moves it.

How can a small force cause a large mass to move?

• The direction of the force is important to make an object move, but the amount of

  force is not.

• The push on the rock increased the amount of friction, so the rock moved.

• The small push balanced the forces that were keeping the rock in place and caused it

  to move.

• The forces on the rock were balanced, and a small additional force caused them to

  be unbalanced.

On two different days, two students measured the force required to hold a pair of scissors

using a spring scale. How should the results compare?

• The results should be the same because the mass of the scissors and the force of

  gravity are the same.

• The results should be the same because friction does not change between the two

  experiments.

• The results should be different because two people never perform an experiment

  exactly the same way.

• The results should be different because changes in conditions between different days

  will cause the results to change.