Question

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

Answer 1

Given, speed of sound = 340 m/s
Distance = 20 m
Time taken for sound to travel 20 m in the air$=\frac{Distance}{Speed}=\frac{20}{340}=\frac{1}{17}s$
Now, frequency of tuning fork = 280 Hz
i.e., number of vibrations completed in 1 s = 280
Thus, the number of vibrations completed in $\frac{1}{17}s$ $=280\times \frac{1}{17}=16.47$