Haryana PMT Haryana PMT Solved Paper-2007

  • question_answer
    The coefficient of friction between the tyres and the road is 0.25. The maximum speed with which car can be driven round a curve of radius 40 m without skidding is (assume \[g=10m{{s}^{-2}}\]

    A)  \[40m{{s}^{-1}}\]                           

    B)  \[20m{{s}^{-1}}\]

    C)  \[15m{{s}^{-1}}\]                           

    D)  \[10m{{s}^{-1}}\]

    Correct Answer: D

    Solution :

                    Key Idea Force of friction provides the necessary centripetal force. For turning around a curve, centripetal force is provided by friction, so                 \[\frac{m{{v}^{2}}}{r}<f\]                 \[\frac{m{{v}^{2}}}{r}<\mu mg\] \[\Rightarrow \]               \[v<\sqrt{\mu gr}\] SO that        \[{{v}_{\max }}=\sqrt{\mu gr}\] Substituting,     \[\mu =0.25,\]    \[r=40m,\] \[g=10m{{s}^{-2}},\] we get                 \[{{v}_{\max }}=10\,m{{s}^{-1}}\].


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