A block B is pushed momentarily along a horizontal surface with an initial velocity V. If \(\mu\) is the coefficient of sliding friction between B and the surface, block B will come to rest after a time : 

\(\frac{V}{g\mu}\)

Friction is the retarding force for the block F = ma = \(\mu\)R = \(\mu\)mg

Therefore, from the first equation of motion : v = u – at

0 = v - \(\mu\)g x t

⇒ \(\frac{v}{\mu g} = t\)