A bullet of mass `20 g` and moving with `600 m/s` collides with a block of mass `4 kg` hanging with the string. What is the velocity of bullet when it comes out of block, if block rises to height `0.2 m` after collision?

Options

A. 200 m/s
B. 150 m/s
C. 400 m/s
D. 300 m/s

Answer

A

Explanation

Initial ,K.E.=`(1)/(2)mv^(2)=(1)/(2)xx(20)/(1000)xx600xx600=3600J`
Change in K.E.=P.E.
`(1)/(2)m(v^(2)-v^(2))`=mgh
`implies3600-(1)/(2)xx(20)/(1000)xxv_(1)^(2)=4xx10xx80impliesv_(1)=200m//s`