NEET Sample Paper NEET Sample Test Paper-58

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

    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 :

    [b] \[x=\,\propto \,{{t}^{3}}y=\beta {{t}^{3}}\] \[{{v}_{x}}=3\,\propto \,{{t}^{3}}{{v}_{y}}=3\beta {{t}^{2}}\] \[={{\left( 3a{{t}^{2}} \right)}^{2}}+{{\left( 3\beta {{t}^{2}} \right)}^{2}}\] \[=9{{\alpha }^{2}}{{t}^{4}}+9{{\beta }^{2}}{{t}^{4}}\] \[V=\sqrt{9{{t}^{4}}\left[ {{\alpha }^{2}}+{{\beta }^{2}} \right]}\] \[V=3{{t}^{2}}\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}}\]


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