Which term describes the friction that resists the start of motion between two resting surfaces in contact?

• A. Rolling friction
• B. Sliding friction
• C. Mass
• D. Static Friction

Answer: (D)

When two surfaces are at rest relative to each other, the friction that resists starting to move is static friction. It acts like a holding force that prevents motion until the push you apply exceeds a certain limit. The maximum amount static friction can provide depends on the normal force between the surfaces and a property called the coefficient of static friction. If your push is smaller than that maximum, nothing moves and the friction simply balances the push. Once you push hard enough to overcome that maximum static friction, motion begins and the friction that acts during sliding is called sliding (kinetic) friction, which is usually weaker than the maximum static friction. Rolling friction and mass aren’t describing this resisting-to-start motion scenario.