A brake's a device for applying a force against the friction of the road, slowing or stopping the motion of a machine or vehicle, or alternatively a device to restrain it from starting to move again. The kinetic energy lost by the moving part's usually translated to heat by friction. Alternatively, in regenerative braking, much of the energy's recovered and stored for later use. Note that kinetic energy increases with the square of the velocity (E = 1/2·m·v2 relationship). This means… (More on Brake)