Home › AP Physics C: Mechanics › Physics › Friction, Drag, and Elasticity › Two surfaces are in contact and sliding past one…
Two surfaces are in contact and sliding past one another right now. What is the friction between them called?
AStatic friction
BKinetic friction
CRolling friction
DNormal friction
Answer & Solution
Correct answer: B. Kinetic friction
1. The source names friction between surfaces already sliding relative to each other.
2. When two surfaces are in contact and moving relative to one another, that friction is called kinetic friction.
3. Static friction instead applies when the surfaces are not yet moving relative to each other.
4. Rolling friction and normal friction are not the terms the source uses for this sliding case.
_Source: OpenStax College Physics (CC BY 4.0), Ch 5 "Further Applications of Newton's Laws: Friction, Drag, and Elasticity", section 5.1 Friction_
Related questions
What happens to the downward force of gravity on a skydiver as their speed rises?Which two forces act on a skydiver falling through air, once buoyancy is ignored?What would a nearly friction-free environment save on a large scale?What kind of characteristics of friction are the simple rules taught at school?Which of these is the standard everyday example of kinetic friction acting?Why do two surfaces become warm when they are rubbed together?Adding a heavy box on top of a crate makes it harder to push. Why?Oiling a concrete floor makes a crate easier to move. What has changed?