In the previous problem , the bullet penetrates the block and emerges with speed `v_(0)`.If the block travels `2.5 m` on the rough surface , the value of `v_(0)` is

Options

A. `155 m//s`
B. `205 m//s`
C. `310 m//s`
D. `100 m//s`

Answer

B

Explanation

`m xx 400 + M xx 0 = Mv + mv_(0)` (i)
The block travels `2.5 m` on the rough surface.
`0 = v^(2) - 2 mu gd = v^(2) - 2 xx (1)/(2) xx 10 xx 2.5 rArr v = 5 m//s` in (i)
`10 xx 400 = 390 xx 5 + 10 v_(0) rArr v_(0) = 205 m//s`