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Question: Answered & Verified by Expert
A nucleus of uranium decays at rest into nuclei of thorium and helium. Then :
PhysicsNuclear PhysicsJEE Main
Options:
  • A the helium nucleus has less momentum than the thorium nucleus
  • B the helium nucleus has more momentum than the thorium nucleus
  • C the helium nucleus has less kinetic energy than the thorium nucleus
  • D the helium nucleus has more kinetic energy than the thorium nucleus
Solution:
1171 Upvotes Verified Answer
The correct answer is: the helium nucleus has more kinetic energy than the thorium nucleus
In an explosion a body breaks up into two pieces of unequal masses both part will have numerically equal momentum and lighter part will have more velocity. $\mathrm{U} \rightarrow \mathrm{Th}+\mathrm{He}$

$$

\mathrm{KE}_{\mathrm{Th}}=\frac{\mathrm{P}^{2}}{2 \mathrm{~m}_{\mathrm{Th}}}, \mathrm{KE}_{\mathrm{He}}=\frac{\mathrm{P}^{2}}{2 \mathrm{~m}_{\mathrm{He}}}

$$

sinc $\mathrm{m}_{\mathrm{He}}$ is less so $\mathrm{KE}_{\mathrm{He}}$ will be more.

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