NEET Sample Paper NEET Sample Test Paper-78

  • question_answer
    The coordinates of a moving particle at any time t are given by \[\operatorname{x}=\alpha {{t}^{3}}\,\,and\,\,y=\beta {{t}^{3}}\]. The speed of the particle at time t is given by

    A)  \[3t\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}}\]              

    B)  \[3{{t}^{2}}\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}}\]

    C)  \[{{t}^{2}}\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}}\]             

    D)  \[\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}}\]

    Correct Answer: B

    Solution :

    Given \[\operatorname{x}=\alpha {{t}^{3}},\,\,y=\beta {{t}^{3}}\] \[{{v}_{x}}=\frac{dx}{dt}=3\,\alpha {{t}^{2}}\] \[{{v}_{y}}=\frac{dy}{dt}=3\,\beta {{t}^{2}}\] \[{{\operatorname{v}}_{R}} =Resultant velocity\] \[=\,\,\,\sqrt{v_{x}^{2}+v_{y}^{2}}\,\,=\,\,3{{t}^{2}}\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}}\]


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