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MGIMS WARDHA MGIMS WARDHA Solved Paper-2009

  • question_answer
    A man stands in a narrow, steep-sided valley. When he shouts he hears two echoes, one after 1 sand other after 2s. If the velocity of sound in air is 330 m/s, the width of the valley is

    A)  330m                                   

    B)  495m

    C)  660m                                   

    D)  990m

    Correct Answer: B

    Solution :

                     Let\[{{s}_{1}}\]and\[{{s}_{2}}\]be the distances of man from either side of valley, then \[2{{s}_{1}}=v{{t}_{1}}\]and\[2{{s}_{2}}=v{{t}_{2}}\] \[\Rightarrow \]\[2({{s}_{1}}+{{s}_{2}})=v({{t}_{1}}+{{t}_{2}})\] \[\Rightarrow \]\[{{s}_{1}}+{{s}_{2}}=\frac{v({{t}_{1}}+{{t}_{2}})}{2}\] \[\therefore \]  \[d={{s}_{1}}+{{s}_{2}}=\frac{330\times (1+2)}{2}\] \[\Rightarrow \]               \[d=\frac{330\times 3}{2}=495\,m\]


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