We witness in our day-to-day life the frictional force taking place in moving bodies which are in interaction. This is called kinetic friction. Rolling friction and sliding friction falls under this topic.
The Retarding force observed as kinetic friction in the two moving aircraft as they touch with each other. The kinetic friction is expressed as
Where,
Fk is Force of kinetic friction
the coefficient of kinetic friction is μk
the normal force is Fn
Kinetic friction formula is handy for questions to compute the friction amid the bodies which are in motion. The unit of frictional force is newton (N) and coefficient of kinetic friction will be a unit-less quantity.