A shell of mass `200g` is ejected from a gun of mass `4 kg` by an explosion that generate `1.05 kJ` of energy. The initial velocity of the shell is

Options

A. `40 m//s`
B. `120 m//s`
C. `100 m//s`
D. `80 m//s`

Answer

C

Explanation

`0 = -4 v + 0.2 u rArr v = (0.2 u)/(4)`
`(1)/(2) xx 4 v^(2) + (1)/(2) (0.2)u^(2) = 1.05 xx 1000`
`2((0.2 u)/(4))^(2) + 0.1 u^(2) = 0.105 u^(2) = 1.05 xx 1000`
`u = 100 m//s`