BCECE Engineering BCECE Engineering Solved Paper-2011

  • question_answer
    A constant power P is applied to a particle of mass m. The distance travelled by the particle when its velocity increases from \[{{v}_{1}}\] to \[{{v}_{2}}\] is (neglect friction)

    A) \[\frac{\text{m}}{\text{3P}}\text{(v}\,_{\text{2}}^{\text{3}}\text{-v}\,_{\text{1}}^{\text{3}}\text{)}\]                  

    B)        \[\frac{\text{m}}{\text{3P}}\text{(}{{\text{v}}_{2}}\text{-}{{\text{v}}_{1}}\text{)}\]

    C)   \[\frac{3P}{m}\text{(v}\,_{2}^{2}\text{-v}\,_{1}^{2}\text{)}\]  

    D)        \[\frac{m}{3P}\text{(v}\,_{2}^{2}\text{-v}\,_{1}^{2}\text{)}\]

    Correct Answer: A

    Solution :

     \[P=Fv=mav\] \[a=\frac{P}{mv}\]                 or            \[v\frac{dv}{ds}=\frac{P}{mv}\] or            \[{{v}^{2}}dv=\frac{P}{m}ds\] or            \[\frac{P}{m}\int_{0}^{s}{ds=\int_{{{v}_{1}}}^{{{v}_{2}}}{{{v}^{2}}dv}}\] or            \[\frac{P}{m}s=\frac{1}{3}(v_{2}^{3}-v_{1}^{3})\]                 \[s=\frac{m}{3P}(v_{2}^{3}-v_{1}^{3})\]


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