Question

What is the law of kinetic friction

Answer 1

Answer:

When a body is in rest,static friction is applied on the body.

This friction is equal to the force applied by you to move the body when it is in a state of rest,like if you try to move a 100kg block then the force applied by you to move the body will be equal to the static friction(till the body is in rest).

Once the body is in motion,say you could move the block with some external force ,then kinetic friction will act against the force you are applying to move the body(just as in static friction)

The only difference is that kinetic friction is less than static friction

$f_{k} <f_{s}$

the reason to this is that making a body come in motion is  more difficult

than moving a body that is already in motion(because in static friction i.e. in motion the body has inertia by which the force by $f_{s}$ is less)

Answer 2

Answer:

• If the body is in relative motion then the friction applied on the relative motion is called as kinetic friction.
• kinetic friction is slightly less than the limiting friction.
• It depends on Normal force (N)
• It don't depend upon the type of motion so it's a constant motion.
• fk = ukN