A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 ms-1 . The kinetic energy of the other mass is

Question

A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 ms-1 . The kinetic energy of the other mass is (A) 256 J (B) 486 J (C) 524 J (D) 324 J

Tardigrade Admin · Accepted Answer

Momentum is conserved just before and after the explosion of the bomb. Initial momentum is zero, so the resultant momentum of the exploded pieces should be zero.
That is

m_{1} v_{1} = m_{2} v_{2}

\Rightarrow (18) (6) = 12 (v_{2})

\Rightarrow v_{2} = 9 m / s

∴

the KE of

12 k g

mass

= \frac{1}{2} 12 (9^{2}) = 486 J

Q. A bomb of mass 30kg at rest explodes into two pieces of masses 18kg and 12kg. The velocity of 18kg mass is 6ms−1 . The kinetic energy of the other mass is

256 J

486 J

524 J

324 J

Momentum is conserved just before and after the explosion of the bomb. Initial momentum is zero, so the resultant momentum of the exploded pieces should be zero. That is m1​v1​=m2​v2​ ⇒(18)(6)=12(v2​) ⇒v2​=9m/s ∴ the KE of 12kg mass =21​12(92)=486J

Q. A bomb of mass $30 k g$ at rest explodes into two pieces of masses $18 k g$ and $12 k g$ . The velocity of $18 k g$ mass is $6 m s^{- 1}$ . The kinetic energy of the other mass is