Question

A bomb of 12 kg explodes into two pieces of masses 4 kg and 8kg. The velocity of 8 kg mass is 6 m per second .The kinetic energy of other mass is?

• A. 48 joules
• B. 32 joules
• C. 24 joules
• D. 288 joule

Answer 1

The correct option is D 288 joule

$m=m_1+m_2$, $v=0$ (initially)

$12=4+8$

So, $m_1{v}_1+m_2{v}_2=0$ (conservation of linear momentum)

$\therefore 8\left(6\right)+4\left(v_2\right)=0$

$\therefore 48=-4v_2$

$\therefore v_2=-12m/s$($-$ve indicate in opposite direction)

$\therefore$ kinetic energy of the $4$ kg piece,

$\frac{1}{2}m{v}^2=\frac{1}{2}\times 4\times (-12{)}^2$

$=144\times 2$

$=288$J.