BCECE Medical BCECE Medical Solved Papers-2015

  • question_answer
    A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is 80 \[m{{s}^{-1}}\]. What is the recoil speed of the gun?

    A)  1.6 \[cm{{s}^{-1}}\]         

    B)  0.5 \[cm{{s}^{-1}}\]

    C)  2 \[cm{{s}^{-1}}\]           

    D)  3 \[cm{{s}^{-1}}\]

    Correct Answer: A

    Solution :

    Here, mass of gun, M = 100 kg Mass of shell, m = 0.02 kg Speed of shell, \[v=80\,\,m{{s}^{-1}}\] and let recoil speed of gun = - V As initially both the gun and the shell are at rest before firing, so the initial momentum \[({{P}_{i}})\] of the system = 0 Final momentum (Pf) of the system after firing                 \[=MV+mv=100\,\,V+0.02\times 80\] According to law of conservation of linear momentum,                 \[{{P}_{i}}={{P}_{F}}\]                 \[0=100\,V+1.6\] \[\Rightarrow \] \[V=\frac{-1.6}{100}=0.016\,\,m{{s}^{-1}}\] \[\therefore \]Recoil speed of gun,\[V=0.016\,\,m{{s}^{-1}}=1.6\,\,c{{s}^{-1}}\]


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