Kinetic Friction
Reference from the original Physics I textbook.
- Kinetic Friction
Kinetic friction acts between surfaces sliding relative to each other. In the simple dry-friction model its magnitude is fₖ = μₖN, and its direction opposes their relative sliding.
- Related Glossary Terms
- Index
Reviewed physics notes (1)
These corrections keep the original lesson’s purpose while fixing errors in the source edition.
- Original wording does not specify relative sliding. — Reference 1
Glossary and deeper reading · 3 refreshers
These editorial refreshers supplement the reading. Definitions and examples are added guidance; original source wording and recorded answers remain in their original context.
-
Kinetic friction
Kinetic friction acts between surfaces that slide relative to one another. It opposes their relative slipping and is often modeled with magnitude equal to the kinetic-friction coefficient times the normal force. For example, a rapidly moving belt can exert forward kinetic friction on a slower box sliding on it.
-
Average velocity
Average velocity is the displacement over an interval divided by the elapsed time. It is a vector and need not equal the average speed, which uses total distance. For example, a runner who returns to the starting line has zero average velocity for the full lap.
-
Static friction
Static friction opposes the tendency for relative sliding between surfaces that are not sliding at their contact. In the simple model it adjusts up to a maximum set by the coefficient of static friction and normal force. For example, static friction can push a walking person forward when the foot pushes backward on the ground.