JEE Main & Advanced Physics Work, Energy, Power & Collision Question Bank Work Done by Variable Force

  • question_answer The potential energy of a certain spring when stretched through a distance ?S? is 10 joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance ?S? will be                    [MNR 1991; CPMT 2002; UPSEAT 2000; Pb. PET 2004]

    A)             30

    B)             40

    C)             10       

    D)             20

    Correct Answer: A

    Solution :

                                \[\frac{1}{2}k{{S}^{2}}=10\ J\]    (given in the problem) \[\frac{1}{2}k\left[ {{(2S)}^{2}}-{{(S)}^{2}} \right]=3\times \frac{1}{2}k{{S}^{2}}\]= 3 × 10 = 30 J


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