J & K CET Medical J & K - CET Medical Solved Paper-2009

  • question_answer
    A body, possessing kineric energy T, moving on a rough horizontal surface, is stopped in a distance y. The frictional force exerted on the body is

    A)  Ty                                         

    B) \[\frac{\sqrt{T}}{y}\]

    C)  \[\frac{T}{y}\]                                  

    D) \[\frac{T}{\sqrt{y}}\]

    Correct Answer: C

    Solution :

                     A block of mass m is moving initially with velocity u on a rough surface and due to friction, it comes to rest after covering a distance s Retarding force \[ma=\mu \text{ }mg\] \[\therefore \]                  \[a=\mu g\] From                     \[{{v}^{2}}={{u}^{2}}-2as\] \[\Rightarrow \]                               \[0={{u}^{2}}-2\mu g\]                                 \[\frac{2T}{m}=2\mu gy\]            ...(i)                                                 \[\left[ As\,T=\frac{1}{2}m{{u}^{2}} \right]\] Now, frictional force \[f=\mu \,mg\]         ... (ii) ie, from Eqs. (i) and (ii), we get                                 \[f=\frac{T}{y}\]


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