what do you mean by slowness and fastness ?
Slowness and Fastness are two distinct 'comparative' parameters which are characterized by the speed/velocity of an object or a particle.
Slowness describes a state of motion in which an object is moving with a small speed/velocity or covering smaller distance in a particular interval of time compared to another body.
Fastness, on the other hand, describes the states body such that it possesses a larger magnitude speed or velocity compared to another body (which obviously moving slow).