When a tuning fork [vibrating] is held close to the ear, one hears a faint hum. The same [vibrating tuning fork] is held such that its stem is in contact with the table surface, then one hears a loud sound. Explain.
A man standing in front of a vertical cliff fires a gun. He hears the echo after . On moving closer to the cliff by , he hears the echo after . Calculate the distance of the cliff from the initial position of the man.
