Forces

Friction is a contact force that acts _______ to the surfaces in contact.

• parallel

• perpendicular

• equal

• at an acute angle

When an object is moving, friction acts in the _______ direction as the motion.

• perpendicular

• same

• opposite

• precise

Tags

NGSS.MS-PS2-2

The magnitude of the friction force depends on the force pushing the surfaces together.

• True

• False

The type of friction that prevents an object from moving is called _______ friction.

• rolling

• fluid

• kinetic

• static

A type of friction that occurs when air pushes against a moving object it to decelerate.

• surface area

• air resistance

• velocity

• gravity

How would the absence of friction affect the motion of a marble on a long, straight path?

• The marble's speed would decrease.

• The marble's speed would remain constant.

• The marble's speed would increase.

• The marble would stop immediately.

Polishing two surfaces in contact will reduce the friction between them.

• True

• False

Which of the following is an example of rolling kinetic friction?

• A box sliding across the floor.

• A car skidding to a stop.

• A soccer player making a slide tackle.

• A bike being ridden on a road.

The equation for the force of friction is _______.

• Ff = µF_g

• Ff = µF_N

• Ff = µF_T

• Ff = µF_s

What affect would decreasing the normal force between two objects have on the force of friction?

• The force of friction would increase.

• The force of friction would decrease.

• The force of friction would remain the same.

• The force of friction would disappear completely.