JEE Main & Advanced AIEEE Solved Paper-2004

  • question_answer
    A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2 : 1. The ratio of their nuclear sizes will be

    A) \[{{2}^{1/3}}:1\]              

    B)        \[1:{{3}^{1/2}}\]              

    C)        \[{{3}^{1/2}}:1\]             

    D)        \[1:{{2}^{1/3}}\]

    Correct Answer: D

    Solution :

    Law of conservation of momentum gives \[{{m}_{1}}{{v}_{1}}={{m}_{2}}{{v}_{2}}\] \[\Rightarrow \]               \[\frac{{{m}_{1}}}{{{m}_{2}}}=\frac{{{v}_{2}}}{{{v}_{1}}}\] But         \[m=\frac{4}{3}\pi {{r}^{3}}\rho \]or\[m\propto {{r}^{3}}\] \[\therefore \]  \[\frac{{{m}_{1}}}{{{m}_{2}}}=\frac{r_{1}^{3}}{r_{2}^{3}}=\frac{{{v}_{2}}}{{{v}_{1}}}\] \[\Rightarrow \]               \[\frac{{{r}_{1}}}{{{r}_{2}}}={{\left( \frac{1}{2} \right)}^{1/3}}\]                  \[\left( \because \frac{{{v}_{1}}}{{{v}_{2}}}=\frac{2}{1} \right)\] \[\therefore \]  \[{{r}_{1}}:{{r}_{2}}=1:{{2}^{1/3}}\]


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