How are the wave velocity V, frequency f and wavelength λ of a wave related? Derive the relationship.

Describe a simple experiment to determine the speed of sound in air. What approximation is made in the method described by you?

The time period of a simple pendulum is 2 s. Find it's frequency.

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.