A bullet of mass \(4.2 \times 10^{2} \mathrm{~kg}\), moving at a speed of \(300 \mathrm{~ms}\), gets stuck into a block with a mass 9 times that of th bullet. If the block is free to move without any kind of friction, the heat generated in the process will be
(A) \(45 \mathrm{cal}\)
(B) \(405 \mathrm{cal}\)
(C) 450 cal
(D) \(1701 \mathrm{cal}\)
Ans: (B)
Hint:
\(\mathrm{KE}_{\text {loss }}=\frac{\mathrm{mM}}{2(\mathrm{~m} \mathrm{M})}(\mathrm{v}-0)^{2}=9 \times 4.2 \times 45 \mathrm{~J}=\frac{1701}{4.2}=405 \mathrm{cal}\)
