Friction

What does friction produce?

• light
• sound
• heat
• gravity

What direction does friction act relative to motion?

• in the same direction
• in the opposite direction 
• need more information
• depends on the force

The amount of friction depends on the weight of the objects pressing together.

• True
• False

How can friction be reduced?

• reduce the force acting between the 2 surfaces
• reduce the roughness of the 2 surfaces coming in contact
• use wax, grease or oil
• all of the above are ways of reducing friction

Which of the following is an example of friction that is helpful?

• Brakes used on a bike
• Tires from a car on the road
• Tread on the bottom of your shoes
• All are examples that are helpful

Which of the following is an example of friction that is harmful?

• Pencil marking on paper
• Engine parts wearing out
• sand placed on ice in the winter
• Using an eraser to erase marks

How does friction affect speed?

• more friction decreases speed
• more friction increases speed
• less friction decreases speed
• less friction doesn't affect speed

Rolling friction is _______ than sliding and static friction

• Lesser

• Equal to

• Greater

• None of the above

friction is a _________ force

The factors on which friction depends

• surface area of contact

• roughness of surface

• both a and b

• none of the above