Forces: UNIT REVIEW

What is the force from a surface called?

• normal force

• friction

• weight

• air resistance

If you push a box on a rough surface, and it does not move, the forces are ______________. This means the force of friction is __________ to the applied force.

• balanced, equal

• unbalanced, less

• balanced, less

Imagine you are floating in space in a spacesuit. If you float along at a constant speed, the net force acting on you is...

• Fnet = constant
• Fnet = 9.8 N
• Fnet = 0 N
• Fnet = ma

This is the reason it is possible to pull a table cloth out from underneath a giant turkey at Thanksgiving.

• Net Force

• Force of Gravity

• Mass

• Inertia

Does an object need an outside force to stay in motion?

• Yes, because forces cause motion.
• Yes, because forces cause acceleration.
• No, because an object can move at a constant speed.
• No, because objects can accelerate. 

Newton's 1st Law says if the forces are balanced or if there are no forces you are...

• at rest .
• at a constant speed.
• accelerating.
• either at rest or at a constant speed.

The sum of all the forces acting on an object is

• the net force
• the force of gravity
• zero
• inertia

A push of 20 N can slide a box on the floor. The force of friction is 12 N. What is the net force on the box?

• 20 N
• 32 N
• 8 N
• 12 N

The force of gravity on a 70 kg person is

(assume g = 9.8 m/s^2)

• 70 N

• 686 N

• 750 N

• 100 N

Two people are pushing a car. Each person can exert 100 N. What is the net force on the car if the force of friction is 120 N.

• 0 N
• 20 N
• 60 N
• 80 N