We were doing questions with surface waves on water and as they moved from deep to shallow water it would slow down. So the teacher said the reason is shallow water is more dense than deep water. If this is true, why so. Does measuring density have anything to do with horizontal or vertical? i think that: density mass divided by volume, so it like a ratio. so it should be almost the same except when there is a lot of water where the the weight causes water to compress water on the bottom very little making the volume a bit less and so its density might be a bit more. so i was researching on the internet and came across reason of its height increasing as wave moves to shallow water and it gets a shorter wavelength. since the freq is the same so the speed slows down. v= f [tex]\lambda[/tex] all this is room temperature, tap water.