The period of a wave is the time it takes for one complete cycle of the wave to pass a given point. It is related to the wavelength and the wave speed. The formula to calculate the period of a wave is:
Period = (Wavelength) / (Wave speed)
In this case, you are given the wavelength of the wave as 20 meters. However, the wave speed is not provided. To determine the period, we need the wave speed. If the wave speed is not given, we cannot determine the period.
Please provide the wave speed to calculate the period of the wave.