Force & Motion Vocabulary

Question 1

Sam wants to lift a heavy rock that is too heavy to lift directly. He uses a sturdy wooden stick as a lever. He places the fulcrum 25 cm from the rock and pushes down on the other end of the stick 75 cm from the fulcrum with a force of 30 N. Which statement correctly explains why Sam can lift the rock with only 30 N?

Accepted Answer

Because his push is farther from the fulcrum, it creates a larger moment that can overcome the rock’s weight.

Answer

Because his push is closer to the fulcrum, it creates a larger moment that can overcome the rock’s weight.

Answer

Because the stick’s length makes the rock lighter.

Answer

Because the fulcrum cancels out the rock’s weight.

Question 2

A soccer ball lying still on a flat field is kicked with a horizontal force of 9 N toward the east. At the same time a steady wind pushes the ball with a horizontal force of 9 N toward the north. No other horizontal forces act on the ball. Which statement correctly describes the forces and the ball’s motion?

Accepted Answer

The forces are unbalanced, so the ball accelerates toward the northeast.

Answer

The forces are balanced, so the ball remains at rest.

Answer

The forces are balanced, so the ball rolls east at a constant speed.

Answer

The forces are unbalanced, so the ball rolls east at a constant speed.

Question 3

A tugboat pulls a floating barge with a force of 300 N toward the east. At the same time, the river current pushes the barge with a force of 200 N toward the west. What is the resultant force acting on the barge?

Accepted Answer

100 N toward the east

Answer

500 N toward the east

Answer

100 N toward the west

Answer

No resultant force; the forces cancel each other out

Try three questions

A tugboat pulls a floating barge with a force of 300 N toward the east. At the same time, the river current pushes the barge with a force of 200 N toward the west. What is the resultant force acting on the barge?

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