A block B is pushed momentarily along a horizontal surface with an...

Block will come to rest, if force applied on it. It will vanish due to frictional force acting between block $B$ and surface, i.e., Force applied = Frictional force i.e., $\quad \mu m g=m a$ or $\quad \mu m g=m$\left(\frac{v}{t}\right)$or$t=\frac{v}{\mu g}