JCECE Medical JCECE Medical Solved Paper-2005

  • question_answer
    A particle moves along Y-axis in such a way that its \[y-\]coordinate varies with time \[t\]according to the relation\[y=3+5t+7{{t}^{2}}.\]The initial velocity and acceleration of the particle are respectively:

    A) \[14m{{s}^{-1}},-5\,m{{s}^{-2}}\]

    B)  \[19\,m{{s}^{-1}},-9\,m{{s}^{-2}}\]

    C)  \[-14\,m{{s}^{-1}},-5\,m{{s}^{-2}}\]

    D)  \[5m{{s}^{-1}},14m{{s}^{-2}}\]

    Correct Answer: D

    Solution :

     Key Idea: Rate of change of position is known as velocity and rate of change of velocity is   known as acceleration. Given                         \[y=3+5t+7{{t}^{2}}\] Velocity \[(v)\] is defined as rate of change of displacement, also using\[\frac{d}{dx}{{x}^{n}}=n{{x}^{n-1}},\]we have \[\therefore \] \[v=\frac{dy}{dt}=5+14\,t\] Initial velocity at \[t=0,\]is \[v=5\,m/s.\] Also acceleration \[a=\frac{{{d}^{2}}y}{d{{t}^{2}}}=14\,m/{{s}^{2}}\]


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