CMC Medical CMC-Medical VELLORE Solved Paper-2013

  • question_answer
    A point moves such that its displacement as function of time is given by \[{{x}^{2}}={{t}^{2}}+1.\] Its acceleration at time\[t\]is

    A)  \[\frac{1}{{{x}^{4}}}\]                                   

    B)  \[-\frac{t}{{{x}^{2}}}\]

    C)  \[\frac{1}{x}-\frac{{{t}^{2}}}{{{x}^{3}}}\]                              

    D)  \[\frac{1}{x}-\frac{t}{{{x}^{2}}}\]

    Correct Answer: C

    Solution :

                    \[{{x}^{2}}={{t}^{2}}+t\] Differentiate wrt x \[2\times \frac{dx}{dt}=2t\] \[v=\frac{dx}{dt}=\frac{t}{x}\] \[a=\frac{dv}{dt}\] \[=\frac{x-t\left( \frac{dx}{dt} \right)}{{{x}^{2}}}\] \[=\frac{x-\left( \frac{{{t}^{2}}}{x} \right)}{{{x}^{2}}}\] \[a=\frac{1}{x}-\frac{{{t}^{2}}}{{{x}^{3}}}\]


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