Kinetic friction
Kinetic friction is the type friction that an object is subject to after it is in motion. Kinetic friction is typically lower than static friction.
The force of kinetic friction can be calculated if one knows the coefficient of kinetic friction and the normal force on the object. It can be calculated using the equation <math>F_f = \mu_f \times \ F_n <math>, where Ff is the force of kinetic friction, μf is the coefficient of kinetic friction, and Fn is the normal force on the object.