JEE Main & Advanced Sample Paper JEE Main Sample Paper-27

  • question_answer
    A particle moves along a parabolic path \[y=9{{x}^{2}}\] in such a way that the x-components of 1 velocity remains constant and has a value \[\frac{1}{3}m{{s}^{-1}}\]. The acceleration of the projectile is :

    A)  \[\frac{1}{3}\hat{j}\,m{{s}^{-2}}\]                             

    B)  \[3\hat{j}\,m{{s}^{-2}}\]

    C)  \[\frac{2}{3}\hat{j}\,m{{s}^{-2}}\]                             

    D)  \[2\hat{j}\,m{{s}^{-2}}\]

    Correct Answer: D

    Solution :

    Give equation is: \[y=9{{x}^{2}}\] Since, x-component of velocity remains constant, we have \[\frac{dx}{dt}=\frac{1}{3}\,m{{s}^{-1}}\]                   ?(i) From eq. (i) we have y-component of velocity \[\frac{dy}{dt}\,=18x.\,\frac{dx}{dt}\] \[\frac{{{d}^{2}}y}{d{{t}^{2}}}\,=18{{\left( \frac{dx}{dt} \right)}^{2}}=18{{\left( \frac{1}{3} \right)}^{2}}=2m{{s}^{-2}}\] \[{{a}_{y}}=2\hat{j}\,m{{s}^{-2}}\]


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