Awater wave is a shallow-water wave if the water depth d is less than a/10. it is shown in hydrodynamics that the speed of a shallow-water gd, so waves slow down as they how long does it take a wave to move the last 120 m to the shore? assume that the waves are so small that they don't break before reaching the shore. wave is v= express your answer to two significant figures and include the appropriate units. move into shallower water. ocean waves, with wavelengths of typically 120 m, are shallow-water waves when the water depth is less than 12 m. consider a beach where the depth increases linearly with distance from the shore until reaching a depth of 5.8 m at a distance of 120 m ha ?