How does kenetic energy stop and go by friction?

Answer 1

Let's get started! An object in motion possesses kinetic energy and to bring the object to a stop this kinetic energy must be removed. ... A mechanical brake applies a friction force to convert the kinetic energy of the vehicle into thermal energy which then dissipates into the atmosphere.

Answer 2

A general energy equation can be written as TE = KE + PE + QE; where TE = total energy, KE = kinetic energy, PE = potential energy, and QE = other energy (e.g., friction energy lost).

Let's assume some system has TE = KE + QE total energy (i.e., PE = 0) at the outset. Physics tells us that friction energy is lost from the system as the system moves with some kinetic energy. So we can write:

KE = TE - QE and there you are. As friction energy is lost from the system, it's kinetic energy decreases. In fact, that's a good thing because that's how the brakes on your car bring the car to a stop through the friction energy losses on the brake drums.