BCECE Medical BCECE Medical Solved Papers-2005

  • question_answer
    A block of mass m initially at rest is dropped from a height h on to a spring of force constant k. The maximum compression in the spring is t, then:

    A)  \[mgh=\frac{1}{2}k\,\,{{x}^{2}}\]

    B)  \[mg\,(h+x)=\frac{1}{2}k\,\,{{x}^{2}}\]

    C)  \[mgh=\frac{1}{2}\,k\,\,{{x}^{2}}\]

    D)  \[mg\,(h+x)=\frac{1}{2}\,k\,{{(x+h)}^{2}}\]

    Correct Answer: A

    Solution :

    Key Idea: Potential energy of block at height h is converted into potential energy of spring. When block is at height h, it has potential energy \[mgh\], which is converted into potential energy of spring to conserve energy i.e.,        \[mgh=\frac{1}{2}k\,\,{{x}^{2}}\] where k is force constant of spring.


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