Manipal Medical Manipal Medical Solved Paper-2013

  • question_answer
    When a long spring is stretched by 2 cm, its potential energy is U. If the spring is stretched by 10 cm, the potential energy in it will be

    A)  \[2U\]  

    B)  \[25U\]   

    C)  \[U/5\]

    D)  \[5U\]

    Correct Answer: A

    Solution :

     Potential energy in a stretched spring is given by \[U=\frac{1}{2}K{{x}^{2}}\] \[\frac{{{U}_{1}}}{{{U}_{2}}}={{\left( \frac{{{x}_{1}}}{{{x}_{2}}} \right)}^{2}}\] Given \[{{X}_{1}}=2cm=.02m,\text{ }{{X}_{2}}=10cm=0.1m\] Substituting the values \[\frac{{{U}_{1}}}{{{U}_{2}}}={{\left( \frac{0.02}{0.1} \right)}^{2}}={{\left( \frac{1}{5} \right)}^{2}}=\frac{1}{25}\] \[{{U}_{2}}=25{{U}_{1}}=2U\]


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