Question

A bomb of 12 kg explodes into two pieces of masses 4 kg and 8 kg. The velocity of 8 kg mass is $6 ms^{-1}$. The kinetic energy of the other mass is

• A. 348 J
• B. 332 J
• C. 324 J
• D. 288 J

Answer 1

Answer: (D)

288 J

Answer 2

As the initial momentum of the bomb was zero, therefore after explosion the two parts should possess numerically equal momentum i,e $m_A v_A=m_B V_B$ $\Rightarrow 4v_A= 8\times 6$ $\Rightarrow v_A=12ms^{-1}$ Kinetic energy of the other mass $A=\frac{1}{2}m_A v^2_A=\frac{1}{2}\times 4\times (12)^2$ =288 J