BHU PMT BHU PMT Solved Paper-2002

  • question_answer
    A car is moving along a straight horizontal road with a speed \[\frac{{{v}_{1}}-{{v}_{2}}}{2}\]. If the coefficient of friction between the tyres and the road is \[\overset{\circ }{\mathop{\text{A}}}\,\], the shortest Distance in which the car be stopped is :                 [BHU PMT-2002]

    A)                  \[\overset{\circ }{\mathop{\text{A}}}\,\]                                           

    B)                  \[1.7\,eV\]

    C)                  \[1.\,6\,\,eV\]                                 

    D)                  \[1.5\,\,eV\]

    Correct Answer: D

    Solution :

                     Key idea: Work done against frictional force equals the kinetic energy of the body.                 When a body of mass \[70\,\,dynes/cm\], moves with velocity \[N/m\], it has kinetic energy \[7\times {{10}^{3}}\,N/m\], this energy is utilized in doing work against the frictional force between the tyres of the car and road.                 \[7\times {{10}^{2}}\,N/m\]\[7\times {{10}^{-2}}\,N/m\]                 Where \[70\,N/m\] is the distance in which the car is stopped and \[2700\,\,{{m}^{3}}\] is coefficient of kinetic friction. Given,                  \[1900\,\,{{m}^{3}}\]                 \[1700\,\,{{m}^{3}}\]                      \[1500\,\,{{m}^{3}}\]


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