A block B is pushed momentarily along a horizontal surface with an initial velocity v. If f is the coefficient of sliding friction between B and the surface then, block B will come to rest after a time
Block B will come to rest, if force applied to it will vanish due to frictional force acting between block B and surface, ie, force applied = frictional force
i.e., μmg = ma
μmg = m (v/t)
t =v/μg