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9th Class Science Sound Question Bank Sound Summative Objective Problems

  • question_answer
    Using the sonar, sound pulses are emitted at the surface, the pulses after being reflected from the bottom are detected, if the time interval from the emission to the detection of the sound pulses is 2 seconds, find the depth of the water. (Taking velocity of sound through water = 1531 m/s)

    A)  1500 m                                

    B)  1000 m

    C)  1531 m

    D)  1530 m

    Correct Answer: C

    Solution :

      Let the depth of water be ?d?. Distance travelled by the pulses is going down towards bottom and reflecting upwards to the surface is \[s=2d\] time taken \[t=2s\] Depth of water\[=d=?\] We know, \[s=vt\] \[\Rightarrow \] \[2d=vt\] \[\Rightarrow \] \[d=\frac{vt}{2}\] \[\Rightarrow \] \[d=\frac{1531\times 2}{2}=1531\,m\] \[\therefore \]  Depth of water = 1531 m.            


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