JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2011

  • question_answer
        A particle moving along x-axis has acceleration \[f,\]at time t, given by\[f={{f}_{0}}\left( 1-\frac{t}{T} \right),\] where\[{{f}_{0}}\] and T are constants. The particle at\[t=0,\]has zero velocity. In the time interval between\[t=0,\]and the instant when\[f=0,\]the particles velocity\[({{v}_{s}})\]is

    A)  \[{{f}_{o}}t\]                                    

    B)  \[\frac{1}{2}{{f}_{o}}{{T}^{2}}\]

    C)  \[{{f}_{o}}{{T}^{2}}\]                    

    D)  \[\frac{1}{2}{{f}_{o}}T\]

    Correct Answer: D

    Solution :

                    \[f=\frac{dv}{dt}={{f}_{0}}\left( 1-\frac{t}{T} \right)\] At\[t=0,f={{f}_{0}}\]at\[T={{T}_{0}},f=0\] We have to calculate the velocity of the particle in the time from\[t=0\]to\[t=T\]sec \[\frac{dv}{dt}={{f}_{0}}\left( 1-\frac{t}{T} \right)\]                 \[\int{dv}=\int_{0}^{T}{{{f}_{0}}\left( 1-\frac{t}{T} \right)}dt\]                 \[v={{f}_{0}}\left( t-\frac{{{t}^{2}}}{2T} \right)_{0}^{T}\]                 \[={{f}_{0}}\left[ T-\frac{{{T}^{2}}}{2T} \right]\]                 \[v={{f}_{0}}\left[ T-\frac{T}{2} \right]\] Velocity, \[v={{f}_{0}}\left( \frac{T}{2} \right)\]


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