J & K CET Engineering J and K - CET Engineering Solved Paper-2005

  • question_answer
    A particle moves along x-axis as \[x=4\,(t-2)+a{{(t-2)}^{2}}\] Which of the flowing is true?

    A)  The initial velocity of particle is 4

    B)  The acceleration of particle is \[2a\]

    C)  The particle is at origin at \[t=0\]

    D)  None of the above 

    Correct Answer: B

    Solution :

    Rate of change of displacement is velocity. \[\left( v=\frac{dx}{dt} \right)\] Given, \[x=4\,(t-2)+a{{(t-2)}^{2}}\] Using    \[\frac{d}{dx}{{x}^{n}}=n{{x}^{n-1}},\]we have \[v=\frac{dx}{dt}=4+2a(t-2)\] At \[t=0,\] \[v=4(1-a)\] Acceleration   \[a=\frac{{{d}^{2}}x}{d{{t}^{2}}}\] \[a=\frac{{{d}^{2}}x}{d{{t}^{2}}}=2a\]


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