Unit 3 Motion and Forces Unit Review

Tom is learning about Newton's Laws of Motion. He and his classmates experienced four different activities, as described in the chart. Which activity illustrates Newton's Third Law of Motion?

• j

• K

• L

• M

The diagram shows a girl jumping on a trampoline. What causes the girl to move upward?

• a reaction force

• a gravitational force

• inertia

• mass

The diagram shows a firefighter operating a hose. The arrows show the forces acting on the hose. Which statement describes the situation in the diagram.

• Since the firefighter is at rest, he does not move as he operates the hose.

• the hose has very little friction, making it slide toward the firefighter

• The firefighter's mass decreases the force of the water escaping from the hose.

• The water escaping from the hose exerts and equal and opposite force on the hose.

Which one of Newton's Laws states, "A body at rest tends to remain at rest, and a body in motion tends to remain in motion, unless acted upon by an unbalanced force?"

• Newton's First Law of Motion

• Newton's Second Law of Motion

• Newton's Third Law of Motion

• Newton's Fourth Law of Motion

When a constant unbalanced force acts on an object in the direction of the motion, what initially happens to the object's speed?

• it decreases

• it increases

• it decreases then increases

• it remains the same

If the mass of a moving object could be halved, what would happen to the inertia of the object?

• it would remain unchanged

• it would be quadrupled

• it would be halved

• it would be doubled

What will happen to an object in motion with no unbalanced force acting on it?

• It will continue to accelerate until it reaches the speed of light.

• It will gradually slow down and come to a rest.

• It will continue to move at a constant speed.

• It will initially accelerate but gradually slow down until it comes to a rest.

a rocket's action is to push down on the ground with the force of its powerful engines, and the reaction is that the ground pushes the rocket upwards with an equal force. Which law best explains this event?

• The Law of Universal Gravity

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

Which example illustrates inertia?

• rock stopping after rolling down a hill

• ball bouncing on a hard surface

• drink spilling after car comes to a sudden stop

• person standing after sitting in a chair

Jasmine is driving a car and has a mas of 60 kg. Laura is her passenger and has a mass of 90 kg. Jasmine suddenly brakes to avoid hitting a deer. Who experiences the greatest force due to the seat belt?

• Jasmine. She has the least mass.

• Laura. She has the greatest mass.

• Laura. She has the greatest speed.

• Jasmine. She has the least speed.