AMU Medical AMU Solved Paper-2011

  • question_answer
    4 J of work is required to stretch a spring through 10 cm beyond its unstretched length. The extra work required to stretch it through additional 10 cm shall be

    A)  4 J                                         

    B)  8 J

    C)  12 J                                       

    D)  16 J

    Correct Answer: D

    Solution :

                     Total work done in increasing the length by \[l\]                 \[W=\frac{1}{2}\frac{YA}{L}{{t}^{2}}\]                 or            \[W\propto {{l}^{2}}\]                 \[\therefore \]  \[\frac{{{W}_{1}}}{{{W}_{2}}}=\frac{l_{2}^{2}}{l_{2}^{2}}\] Let the initial length be 10.                 \[\frac{4}{{{W}_{2}}}=\frac{10\times 10}{20\times 20}\]                 \[{{W}_{2}}=16J\]


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