BHU PMT BHU PMT Solved Paper-2002

  • question_answer
    The potential energy of a body is given by \[A-B{{x}^{2}}\] (where \[\left( E \right)\] is the displacement). The magnitude of force acting on the particle is :                                                                                                       [BHU PMT-2002]

    A)                  Inversely proportional to \[\left( v \right)\]

    B)                  Proportional to \[\left( F \right)\]

    C)                  Proportional to \[F{{v}^{-2}}\]

    D)                  Constant

    Correct Answer: C

    Solution :

                     Key Idea : Conservative force can be represented by potential energy function.                 If a force acting on an object is a function of position only, it is said to be a conservative force and it can be represented by a potential energy function and which for a one dimensional case satisfies the derivative condition.                                 \[\Rightarrow \]                               Given, \[F=\frac{mg\left( h+d \right)}{d}\]                 \[F=mg\left( 1+\frac{h}{d} \right)\]                         \[\Delta \,m\]                 \[\Delta \,E\]                     \[\Delta \,E=\left( \Delta \,\,m \right){{c}^{2}}\]                 \[\therefore \]                  \[=\frac{\text{Dimension of energy}}{{{\left( \text{Dimension of velocity} \right)}^{2}}}\]                 Hence, magnitude of force is proportional to      \[\text{Energy}=\left[ ML{{T}^{-2}}\,\,L \right]=\left[ M{{L}^{2}}\,\,{{T}^{-2}} \right]\].


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