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

  • question_answer
    A gun fires a bullet of mass \[m\] with velocity\[v\]. The mass of the gun is \[M\] and it recoils with velocity\[V\]. If the kinetic energy of the bullet is \[{{E}_{b}}\] and that of the gun is\[{{E}_{g'}}\] identify the relation between\[{{E}_{b}}\]and\[{{E}_{g'}}\].

    A) \[{{E}_{b}}={{E}_{g}}\]         

    B)        \[{{E}_{b}}<{{E}_{g}}\]

    C) \[{{E}_{b}}>{{E}_{g}}\]           

    D)        \[{{E}_{b}}\ge {{E}_{g}}\]

    Correct Answer: C

    Solution :

     \[{{E}_{b}}=\frac{1}{2}m{{v}^{2}},\,\,{{E}_{g}}=\frac{1}{2}M{{V}^{2}}\] Since\[KE\propto {{V}^{2}}\]and\[v>V,\,\,{{E}_{b}}>{{E}_{g}}\]


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