EAMCET Medical EAMCET Medical Solved Paper-2010

  • question_answer
    The kinetic energy K of a particle of mass m moving along a circle of radius R depends on distance covered s as K= as2. Then the acceleration of particle is given by

    A)                  \[\frac{2as}{m}{{\left( 1+\frac{{{s}^{2}}}{{{R}^{2}}} \right)}^{1/2}}\]                       

    B)                  \[\frac{2as}{m}{{\left( 1-\frac{{{s}^{2}}}{{{R}^{2}}} \right)}^{1/2}}\]

    C)                  \[\frac{2a{{s}^{2}}}{mR}\]                                          

    D)                  \[\frac{2as}{m}\]

    Correct Answer: A

    Solution :

                     According to given problem                 \[\frac{1}{2}m{{v}^{2}}=a{{s}^{2}}\]                        \[v=s\sqrt{\frac{2a}{m}}\]                 So           \[{{a}_{R}}=\frac{{{v}^{2}}}{R}=\frac{2a{{s}^{2}}}{mR}\]                 Furthermore as                 \[{{a}_{t}}=\frac{dv}{dt}=\frac{dv}{ds}\times \frac{ds}{dt}=v\frac{dv}{ds}\]                 \[{{a}_{t}}=\left[ s\sqrt{\frac{2a}{m}} \right]\left[ \sqrt{\frac{2a}{m}} \right]\]                 \[\left[ \because v=s\sqrt{\frac{2a}{m}}\text{ and }\frac{dv}{ds}=\sqrt{\frac{2a}{m}} \right]\]                 \[{{a}_{t}}=\frac{2as}{m}\]                 Acceleration \[a=\sqrt{a_{R}^{2}+a_{t}^{2}}\]                                 \[=\sqrt{\left[ \frac{2a{{s}^{2}}}{mR} \right]+{{\left[ \frac{2as}{m} \right]}^{2}}}\]                                 \[=\frac{2as}{m}\sqrt{\left( 1+\frac{{{s}^{2}}}{{{R}^{2}}} \right)}\]


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