Friction 1

What is friction?

• Friction is the force that opposes the relative motion of two surfaces in contact.
• Friction is the temperature increase caused by two surfaces rubbing together.
• Friction is the energy lost when two surfaces are separated.
• Friction is the force that enhances the motion of two surfaces in contact.

Which of the following increases friction?

• Smoother surfaces
• Lower normal force
• Increased temperature
• Increased surface roughness or greater normal force.

What is the coefficient of friction?

• The coefficient of friction is always greater than one.
• The coefficient of friction is a dimensionless value that represents the ratio of the frictional force to the normal force.
• The coefficient of friction is a measure of mass.
• The coefficient of friction is the force applied to an object.

Which type of friction is usually greater?

• Fluid friction
• Kinetic friction
• Static friction
• Rolling friction

If a 10 N force is required to keep a 5 kg block moving at constant speed, what is the coefficient of kinetic friction?

• 0.75
• 0.5
• 0.204
• 0.1