Forces

Equal forces are-

• forces that have the same strength.

• forces that have different strengths.

• one force that acts on both moving and nonmoving objects.

• a force between surfaces that slows objects or stops them from moving.

Unequal forces are-

• forces that have the same strength.

• forces that have different strengths.

• one force that acts on both moving and nonmoving objects.

• a force between surfaces that slows objects or stops them from moving.

Friction is-

• forces that act together on an object without changing its motion

• forces that do not cancel each other out and cause an object to change its motion.

• one force that acts on both moving and nonmoving objects. A force that pulls objects.

• a force between surfaces that slows objects or stops them from moving.

Which picture is an example of equal forces?

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Which picture is an example of friction?

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In the illustration, a brick is tied to the end of a rope. Why is the brick not moving?

• The force of gravity is gone because the brick is held up by the rope.

• The force of gravity on the brick is equal to the upward pull of the rope.

• Both the force of gravity and the rope pull the brick upward.

• The force of gravity is too strong for the brick to move.

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A mouse, a dog, and a boy each try to roll the same heavy bowling ball. The table shows the results. When were unequal forces acting on the ball?

• when both the dog and boy rolled the ball

• only when the mouse tried to roll the ball

• only when the dog rolled the ball

• when all three bowlers rolled or tried to roll the ball

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Julio is pushing hard against the wall. Which arrow shows the force of the wall on Julio?

• Arrow A

• Arrow B

• Arrow C

• Arrow D

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Portia is holding a ball in her hand. When she lets go of the ball, what set of forces will be acting on the ball? Fill-in-the-blank below.

When Portia lets go of the ball, gravity will be the remaining force on the ball, and it will be a(n) _________ force. As a result, the ball will accelerate downward.

• equal

• unequal

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Marlene and Trevor are pushing equally hard on a heavy crate. Why is the crate not moving?

• The forces are in the opposite direction, so they are unequal forces.

• The forces are in the same direction, so the forces are unequal.

• The forces are in the opposite direction, so the forces are equal.

• The forces are contact forces, so the net force cannot be calculated.

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