Newton's Third Law

Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.

• Always true

• Sometimes true

• Never true

Kids pull on a wagon. As they pull there is a force acting

• upon the wagon but not on the kid

• upon the kid but not on the wagon

• upon the kid and the wagon

Forces always occur

• as single quantities

• in pairs

• by themselves

A dog plays with a ball. Consider the action force the dog touching the ball. What is the reaction force?

• The friction of the ground on the ball.

• The ball pushing the ground.

• The ground pulling the dog.

• The ball touching the dog.

A person is attracted towards the center of Earth by a 440N gravitational force. The force with which Earth is attracted toward the person is

• More than 440N

• Less than 440N.

• The same, 440N.

An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is

• larger.

• the same.

• smaller

• need more information to say.

If a horse pulls on a wagon at rest, the wagon pulls back equally on the horse. Can the wagon be set into motion?

• Yes, because there is a net force acting on the wagon.

• Yes, because there is a time delay between action and reaction.

• No, because the forces cancel each other.

• Yes, because the horse's pull on the wagon is larger than the wagon's pull on the horse.

A large truck and a small car traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be

• the small car

• the large truck

• neither, both are the same.

According to Newton's third law, if you push gently on something, it will push

• gently on something else.

• on you only if you aren't moving.

• gently on you

• on something only under the right conditions.

Earth pulls on the moon, and similarly the moon pulls on Earth. This is evidence that the

• Earth and moon are simply pulling on each other.

• Earth's and moon's pulls comprise an action-reaction pair.

• both a and b

• neither a or b