9th Class Science Work and energy Question Bank Work, Energy and Power

  • question_answer
    Which of the following graphs closely represents the kinetic energy (K) of a freely falling body and its height (h) above the ground?

    A)  

    B)

    C)

    D)

    Correct Answer: A

    Solution :

                    \[\frac{m{{v}^{2}}}{r}=\frac{{{k}^{2}}}{{{r}^{2}}}\] \[\therefore \]  \[\frac{1}{2}m{{v}^{2}}=\frac{1}{2}\frac{{{k}^{2}}}{r}\]                           \[=\] kinetic energy of the particle Potential energy of the particle\[=-\frac{k}{r}\] \[\therefore \]Total energy\[E=K.E.+P.E.\]                            \[=\frac{k}{2r}-\frac{k}{r}=-\frac{k}{2r}\] \[\therefore \]      \[|E|\,\,=\frac{k}{2r}\]


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