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9th Class Science Sound Question Bank Sound

  • question_answer
    A stone is dropped from the top of a tower of height\[300\,\,m\]into a pond at the base of the tower. When will the sound of the splash be heard at the top? (Velocity of sound \[=340\,\,m\,\,{{s}^{-1}}\] and\[g=9.8\,\,m\,\,{{s}^{-2}}\])

    A) \[5.6\,\,s\]         

    B)        \[8.7\,\,s\]  

    C) \[5.4\,\,s\]                     

    D)        \[6.7\,\,s\]

    Correct Answer: B

    Solution :

    \[{{T}_{d}}=\sqrt{\frac{2h}{g}}=\sqrt{\frac{2\times 300}{9.8}}=\sqrt{61.2}\] Let \['t'\] be the time taken for the splash of sound to be heard.             \[{{t}_{d}}+t=\sqrt{\frac{2h}{g}}+\frac{300}{340}=\sqrt{61.2}+\frac{15}{17}\]


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