4. A bullet of mass 50 g is fired horizontally at a wooden block of mass 4.95 kg which is lying at rest on a rough horizontal surface. The bullet enters the block at \(400 \mathrm {~ms} ^ { - 1 }\) and becomes embedded in the block.
- Find the speed with which the block begins to move.
Given that the block decelerates uniformly to rest over a distance of 4 m ,
- show that the coefficient of friction is \(\frac { 2 } { g }\).