Question

how many vibrations will a turning fork of frequency 280hz complete during the time sound travels forward in air by 20m . take speed of sound in air as 340

Answer 1

speed=340m/s
distance=20m
threfore, time=dist/speed
                     =340/20
                     =17s

the frequency=280hz
therefore, no. of vibrations in 1s=280

Therefore, total no. of vibrations in 20m=280 x 17
                                                               =4760 vibrations.