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NEET Sample Paper NEET Sample Test Paper-18

  • question_answer
    Two trains, one is coming towards and another is going away from an observer both at 4 m/s produce a whistle simultaneously of frequency 300 Hz. Find the number of beats produced:

    A)    5                              

    B)   6

    C)    7                              

    D)    12

    Correct Answer: C

    Solution :

    For coming train \[n'=n\left\{ \frac{v}{v-{{v}_{5}}} \right\}\]and for going train" \[=n\left\{ \frac{v}{v+{{v}_{5}}} \right\}\]             \[n=n'-n=n\left[ \frac{v}{v-{{v}_{5}}}-\frac{v}{v+{{v}_{5}}} \right]\]             =7 (after putting values, Hence, the correction option is [c].


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