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9th Class Science Sound Question Bank Sound

  • question_answer
    A boy stands facing a high wall at a distance of \[85\,\,m\] from it and then blows a whistle. Calculate the time interval when he hears an echo. (Speed of sound\[=340\,\,m\,\,{{s}^{-1}}\]).

    A) \[1\,\,s\]            

    B)        \[2\,\,s\]

    C) \[0.5\,\,s\]                       

    D)        \[3\,\,s\]

    Correct Answer: C

    Solution :

    \[v=\frac{2d}{t}\Rightarrow 340=\frac{2\times 85}{t}\Rightarrow t=\frac{2\times 85}{340}=0.5\,\,s\]


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