J & K CET Medical J & K - CET Medical Solved Paper-2014

  • question_answer
    The bus moving with a speed of 42 km/h is brought to a stop by brakes after 6m. If the same bus is moving at a speed of 90 km/h, then the minimum stopping distance is

    A)  15.48 m

    B)  18.64 m

    C)  22.13 m

    D)  27.55 m

    Correct Answer: D

    Solution :

     \[u=42\times \frac{5}{18}=11.66\,m/s\] and \[v=0\] So,    \[{{S}_{1}}=6m\] when, \[u=90\times \frac{5}{18}=25m/s\] and     \[v=0\] Then,   \[{{S}_{2}}=?\] For first case \[\Rightarrow \] \[{{v}^{2}}={{u}^{2}}+2a{{s}_{1}}\] \[0={{(11.66)}^{2}}+2a\times 6\] \[({{s}_{1}}=6m)\] \[a=\frac{-11.66\times 11.66}{12}\] \[a=-11.33m/{{s}^{2}}\] For second case \[{{v}^{2}}={{u}^{2}}+2a{{s}_{2}}\] \[0={{(25)}^{2}}+2(-11.33)\times {{s}_{2}}\] \[{{s}_{2}}=\frac{625}{2\times 11.33}=27.5\,m\]


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