Friction and Gravity

When does sliding friction occur?

• When two surfaces rub against each other.

• When an object is on wheels.

• When one surface is solid and the other is liquid.

A rougher surface does what to the friction of a surface?

• increases friction

• decreases friction

Rolling friction happens when what happens?

• When liquid runs over a hard surface.

• When one surface rolls over another surface.

• One surface is smooth and the other surface is rough.

The amount of friction in rolling friction is __________ than sliding friction.

• greater

• lesser

Fluid Friction occurs in 

• Both Liquid and Gasses

• Gasses only

• Liquids only

When the angle of a surface in air increase the amount of friction on the surface we call this what?

• Sliding Friction with Air

• Normal Force

• Air Resistance (Fluid Friction)

The more surface area the less air resistance present.

• True

• False

What has a gravitational pull?

• All objects with any mass 

• Object with a large Mass 

As _________ increases, air resistance increases. 

• velocity 

• gravity 

• acceleration