A skipper on a boat notices wave crests passing his anchor chain every 5 s. He estimates the distance between wave crests to be 15 m. He also correctly estimates the speed of the waves.
(a) Show that his estimation of wave speed is 3 m/s by the classic formula for speed, distance divided by time.
(b) Show that his estimation of wave speed is 3 m/s by frequency × wavelength.