The separation between two consecutive crests in a transverse wave is 100 m. If wave velocity is 20 m s^-1, find the frequency of wave.

A longitudinal wave travels at a speed of 0.3 m s^-1 and the frequency of a wave is 20 Hz. Find the separation between the two consecutive compressions.

An observer A fires a gun and another observer B at a distance 1650 m away from A hears it's sound. If the speed of sound is 330 m s^-1, find the time when B will hear the sound after firing by A.

The time interval between a lightning flash and the first sound of thunder is 5 s. If the speed of sound in air is 330 m s^-1 , find the distance of flash from the observer.