A tsunami wave travelling in deep ocean water has a wavelength of 200 km and a frequency of 0.020 Hz.
(a) Calculate its speed in deep water.
(b) As the wave approaches shallow coastal water its speed decreases to 60 % of the deep-water value, while its frequency remains the same. Determine its wavelength near the coast.
(c) If the crest of the wave reaches a coastal point at time t=0, how many complete oscillations occur at that point during the next 20 minutes?
(d) Comment briefly on how the change in wavelength from deep to shallow water influences the potential impact of the tsunami on the coastline.