A 12 kg bomb at rest explodes into two piece of 4 kg and 8kg . If the momentum of 4kg piece is 20Ns, the kinetic energy of the 8kg piece I

Options

A. 25j
B. 20j
C. 50j
D. 40j

Answer

a

Explanation

:M=12kg, u=0, `m_(1)=4kg,m_(2)=8kg`
`p_(1)=20N_(s),P_(2)=? K_(2)=?`
Using linear momentum conservation principle
`P=P_(1)+P_(2)`
`Rightarrow0=P_(1)+P_(2)RightarrowP_(2)=-P_(1)=-20Ns`
Kinetic energy of 8kg piece `K_(2)= (p_(2)^(2))/(2m)`
`K_(2)= (-20)^(2)/(2xx8)= (400)/(16)=25J`