JEE Main & Advanced Physics Elasticity Question Bank Work Done in Stretching a Wire

  • question_answer
    If the potential energy of a spring is V on stretching it by 2 cm, then its potential energy when it is stretched by 10 cm will be                                              [CPMT 1976]

    A) V/25

    B)                             5V

    C)                 V/5         

    D)                 25V

    Correct Answer: D

    Solution :

    \[U=\frac{1}{2}\left( \frac{YA}{L} \right)\,{{l}^{2}}\] \ \[U\propto {{l}^{2}}\]             \[\frac{{{U}_{2}}}{{{U}_{1}}}={{\left( \frac{{{l}_{2}}}{{{l}_{1}}} \right)}^{2}}={{\left( \frac{10}{2} \right)}^{2}}=25\]Þ \[{{U}_{2}}=25{{U}_{1}}\] i.e. potential energy of the spring will be 25 V


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