Manipal Engineering Manipal Engineering Solved Paper-2013

  • question_answer
    A car is moving along a straight horizontal road with a speed\[{{\upsilon }_{0}}\]. If the coefficient of friction between the tyres and the road is\[\mu \], the shortest distance in which the car be stopped is

    A) \[\frac{v_{0}^{2}}{\mu }\]                                           

    B) \[{{\left( \frac{{{v}_{0}}}{{{\mu }_{g}}} \right)}^{2}}\]

    C) \[\frac{v_{0}^{2}}{{{\mu }_{g}}}\]                            

    D)        \[\frac{v_{0}^{2}}{2{{\mu }_{g}}}\]

    Correct Answer: D

    Solution :

    Work done against frictional force equals the kinetic energy of the body. when a body of mass m, moves with velocity\[v,\]it has kinetic energy\[k=\frac{1}{2}m{{v}^{2}}\], this energy is utilized in doing work against the frictional force between the tyres of the car and road. \[\therefore \]kinetic energy = work done against friction force                 \[\frac{1}{2}{{m}^{2}}=\mu \,\,mgs\] where\[s\]is the distance in which the car is stopped and u is coefficient of kinetic friction. Given    \[v={{v}_{0}}\]                 \[s=\frac{v_{0}^{2}}{2\mu \,\,g}\]


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