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Question: Answered & Verified by Expert
A bullet of mass $\mathrm{m}$ is fired horizontally into a large sphere of mass $\mathrm{M}$ and radius $\mathrm{R}$ resting on a smooth horizontal table.


The bullet hits the sphere at a height $\mathrm{h}$ from the table and sticks to its surface. If the sphere starts rolling without slippng immediately on impact, then
PhysicsCenter of Mass Momentum and CollisionKVPYKVPY 2013 (SB/SX)
Options:
  • A $\frac{\mathrm{h}}{\mathrm{R}}=\frac{4 \mathrm{~m}+3 \mathrm{M}}{2(\mathrm{~m}+\mathrm{M})}$
  • B $\frac{\mathrm{h}}{\mathrm{R}}=\frac{\mathrm{m}+3 \mathrm{M}}{\mathrm{m}+2 \mathrm{M}}$
  • C $\frac{\mathrm{h}}{\mathrm{R}}=\frac{10 \mathrm{~m}+7 \mathrm{M}}{5(\mathrm{~m}+\mathrm{M})}$
  • D $\frac{h}{R}=\frac{4 m+3 M}{m+M}$
Solution:
2997 Upvotes Verified Answer
The correct answer is: $\frac{\mathrm{h}}{\mathrm{R}}=\frac{10 \mathrm{~m}+7 \mathrm{M}}{5(\mathrm{~m}+\mathrm{M})}$
Apply conservation of linear momentum
$$
\begin{array}{l}
m v=(m+M) v_{0} \\
m v \sin \theta R=\left(\frac{2}{5} M R^{2}+m R^{2}\right) \omega_{0} \\
m v\left(\frac{h-R}{R}\right) R=\frac{(2 M+5 M)}{5} \omega_{0} R^{2} \\
(m+M)(h-R) \omega_{0} R=\frac{(2 M+5 M)}{5} \omega_{0} R^{2} \\
\frac{h}{R}=\frac{(10 m+7 M)}{5(m+M)}
\end{array}
$$

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