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

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

(a) gμ/V

(b) g/V

(c) V/g

(d) V/(gμ)

[NEET 2007]

Final Velocity is zero. Initial velocity given as v

\[v = u + at\]\[0 = v - (\mu g)t\]\[t = \frac{v}{\mu g} \]

\[ F_{\text{friction}} = \mu N = \mu mg \]\[ ma = \mu mg \]\[a = \mu g \]

Retardation, acting opposite to the velocity, so 'a' taken as negative.