A bullet of mass `10g` moving horizontally with a velocity of `400 ms^(-1)` strickes a wooden block of mass `2 kg` which is suspended by a light inextensible string of length `5m`. As a result, the center ofgravity of the block is found to rise a vertical distance of `10cm` . The speed of the bullet after it emerges out hirizontally from the block will be

Options

A. 100 `ms^(-1)`
B. 80 `ms^(-1)`
C. 120 `ms^(-1)`
D. 160 `ms^(-1)`

Answer

C

Explanation

Velocity of block `=sqrt(2gh)=sqrt(2xxgxx0.1)=sqrt(2)m//s`
`P_(i)=P_(f)`
`(10xx10^(-3))xx400+0=2xxsqrt(2)+(10xx10^(-3))V`
`V=((4-2sqrt(2)))/(10xx10^(-3))=120m//s`