VMMC VMMC Medical Solved Paper-2006

  • question_answer
    The potential energy of a particle of mass 5 kg moving in the x - y plane is given by \[U=(-7x+24y)\,J,\,x\] and y being in metre. If the particle starts from rest from origin, then speed of particle at t = 2 s is:

    A) 5 m/s                                    

    B) 14 m/s 

    C)        17.5 m/s              

    D)        10 m/s

    Correct Answer: D

    Solution :

    \[F=\frac{-\partial u\,\hat{i}}{\partial x}\frac{-\partial u\,\hat{j}}{\partial y}=7\hat{i}-24\hat{j}\] \[\therefore \]\[{{a}_{x}}=\frac{{{F}_{x}}}{m}=\frac{7}{5}=1.4\,m/{{s}^{2}},\]along positive \[x-\]axis \[{{a}_{y}}=\frac{{{F}_{y}}}{m}=-\frac{24}{5}\] \[=4.8\,m./{{s}^{2}}\]along negative \[y-\]axis \[\therefore \]  \[{{v}_{x}}={{a}_{x}}t=1.4\times 2=2.8\,m/s\] and        \[{{v}_{y}}=4.8\times 2=9.6\,m/s\] \[\therefore \]  \[v=\sqrt{v_{x}^{2}+v_{y}^{2}}=10\,m/s\]


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