NEET Sample Paper NEET Sample Test Paper-82

  • question_answer
    A ball of mass M is fixed to one end of a light spring of force constant k and unstretched length L as shown in figure. If the system is rotated about the other end of the spring with an angular velocity \[\omega \] in frictionless horizontal surface then the increase in length of the spring will be

    A)  \[\frac{M{{\omega }^{2}}L}{M{{\omega }^{2}}-k}\]             

    B)  \[\frac{M{{\omega }^{2}}L}{k-M\,{{\omega }^{2}}}\]

    C)  \[\frac{M{{\omega }^{2}}}{k}\]                                  

    D)  \[\frac{kL}{M{{\omega }^{2}}}\]

    Correct Answer: B

    Solution :

    Let AL be increase in length of spring. Particle will move on a circular path of radius\[\left( L + \Delta L \right)\]. Restoring force due to spring \[=\,\,k\,\Delta L\] By force balance \[\operatorname{M}{{\omega }^{2}}(L +\,\,\Delta L) =\,\,k\Delta L\,\,\,\Rightarrow \,\,\Delta L = \,\frac{M\,{{\omega }^{2}}\cdot L}{k-M\,{{\omega }^{2}}}\]


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