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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 11

  • question_answer
    A speeding motorcyclist sees traffic jam ahead of him. He slows down to\[36\text{ }km/hour\]. He finds that traffic has eased and a car moving ahead of him at \[18\text{ }km/hour\] is honking at a frequency of \[1392\text{ }Hz\]. If the speeds of sound is \[343\text{ }m/s,\] the frequency of the honk as heard by him will be:

    A) \[1332Hz\] 

    B) \[1372\,Hz\]

    C) \[1412Hz\]          

    D) \[1464\,Hz\]

    Correct Answer: C

    Solution :

    According to Doppler's effect                       Apparent frequency \[n'=n\left( \frac{v+{{v}_{0}}}{v+{{v}_{s}}} \right)=1392\,\left( \frac{343+10}{343+5} \right)\]\[=1412\,Hz\]


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