Which type of friction occurs when an object rolls rather than slides?

Which type of friction occurs when an object rolls rather than slides?

• A. Rolling
• B. Static
• C. Kinetic
• D. Viscous

Answer: (A)

Rolling friction is the resistive force that opposes the motion of a rolling object. When a wheel or ball rolls without slipping, the contact point momentarily has no relative motion, so static friction acts at the contact to prevent slipping. The energy lost in deforming the surfaces and micro-slip in the contact region manifests as rolling friction, which is typically much smaller than sliding (kinetic) friction. That’s why a wheel rolls with less resistance than if it were sliding, making rolling friction the correct concept here.

Rolling friction is the resistive force that opposes the motion of a rolling object. When a wheel or ball rolls without slipping, the contact point momentarily has no relative motion, so static friction acts at the contact to prevent slipping. The energy lost in deforming the surfaces and micro-slip in the contact region manifests as rolling friction, which is typically much smaller than sliding (kinetic) friction. That’s why a wheel rolls with less resistance than if it were sliding, making rolling friction the correct concept here.