Question

How many vibrations will a tuning fork of frequency 280hz complete during the time sound travels forward in air 20m. Take speed of sound in air as 340m/s.

Answer 1

Speed of sound = 340m/s
Frequency = 280Hz
Distance = 20 m 
We know,
Time = Distance/Speed
         = 20 m/ 340 m/s
         = 17 s
∴No. of vibrations completed in 17 s = 280 × 17
                                                           = 4760 ANS