Understanding Friction

Which type of friction occurs when an object is not moving?

• Rolling friction

• Static friction

• Kinetic friction

• Fluid friction

What happens to static friction as more force is applied to an object?

• It decreases

• It remains constant

• It increases

• It disappears

Once static friction is overcome, what type of friction acts on a moving object?

• Fluid friction

• Rolling friction

• Kinetic friction

• Static friction

How does kinetic friction compare to static friction?

• Kinetic friction is always less

• Kinetic friction is sometimes greater

• Kinetic friction is equal to static friction

• Kinetic friction is always greater

What is the coefficient of friction?

• A measure of the weight of an object

• A ratio that describes the force of friction between two surfaces

• A constant value for all materials

• A measure of the force of gravity

Why is kinetic friction generally lower than static friction?

• Because kinetic friction is not affected by speed

• Because static friction does not exist

• Because surfaces interlock less when moving

• Because moving objects have less mass

Which material combination has a higher coefficient of static friction than kinetic friction?

• Rubber on concrete

• Ice on ice

• Steel on steel

• Glass on glass

Why does surface area not affect the force of friction?

• Because friction is only dependent on weight

• Because the pressure compensates for the area

• Because larger areas have more friction

• Because smaller areas have less friction

What happens to the frictional force when an object is placed on a ramp?

• It becomes zero

• It increases due to gravity

• It remains constant

• It decreases due to gravity

Why can't a car stop once it starts sliding?

• Because kinetic friction is greater than static friction

• Because the road is too smooth

• Because kinetic friction is less than static friction

• Because the car is too heavy