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CET Karnataka Medical CET - Karnataka Medical Solved Paper-2010

  • question_answer
    A bat flies at a steady speed of\[4\text{ }m{{s}^{-1}}\]emitting a sound of\[f=90\times {{10}^{3}}Hz\]. It is flying horizontally towards a vertical wall. The frequency of the reflected sound as detected by the bat will be (take velocity of sound in air is\[330\text{ }m{{s}^{-1}}\])

    A)  \[88.1\times {{10}^{3}}Hz\]

    B)  \[87.1\times {{10}^{3}}Hz\]

    C)  \[92.1\times {{10}^{3}}Hz~~~\]

    D)  \[89.1\times {{10}^{3}}Hz\]

    Correct Answer: C

    Solution :

    Frequency of reflected sound heard by the bat \[v=v\left[ \frac{v-({{v}_{0}})}{v-{{v}_{s}}} \right]\] \[=v\left[ \frac{v-{{v}_{0}}}{v-{{v}_{s}}} \right]=v\left[ \frac{v+{{v}_{B}}}{v-{{v}_{b}}} \right]\] \[=v\left[ \frac{330+4}{330-4} \right]90\times {{10}^{3}}\] \[=92.1\times {{10}^{3}}Hz\]


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