Nuclei - Result Question 22

24. A nucleus of uranium decays at rest into nuclei of thorium and helium. Then :

[2015 RS]

(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.

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Answer:

Correct Answer: 24. (d)

Solution:

  1. (d) 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.

$U \to Th+He$

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

since $m _{He}$ is less so $KE _{He}$ will be more.