J & K CET Engineering J and K - CET Engineering Solved Paper-2013

  • question_answer
    The velocity vector of the motion described by the position vector of a particle, \[r=2t\,\,\hat{i}+{{t}^{2}}\hat{j}\]is given by

    A)  \[V=2i+2t\,\hat{j}\]      

    B)  \[V=2t\,\,\hat{i}+2t\,\hat{j}\]

    C)  \[V=t\,\,\hat{i}+{{t}^{2}}\,\hat{j}\]     

    D)  \[V=2\,\,\hat{i}+{{t}^{2}}\,\hat{j}\]

    Correct Answer: A

    Solution :

    Given \[r=2t\,\hat{i}+{{t}^{2\,}}\hat{j}\] Velocity vector \[v=\frac{dr}{dt}\] and using \[\frac{d}{dx}{{x}^{n}}=n{{x}^{n-1}}\] We have, \[\frac{dr}{dt}=2\,\hat{i}+2t\,\hat{j}\]


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