The presence of friction in Kinetic friction is called the "Kinetic friction force". When the force exerted on an object is greater than the maximum Static friction force, the object begins to move. After moving up, if the applied force is reduced, the object will stop moving again. This situation shows that after the movement of the object, there is also a force to prevent the movement of the object, that is, there is friction resistance. The Kinetic friction force generated by such objects is called kinetic friction force.

Kinetic friction force：F_k=μ_k*N

here:

μ_k = Kinetic friction divisor

N = Normal force