# At what speed would you die upon impact with water?

If we hit the water at great speeds, we die.

This is because the water has no time to "move out of the way" and acts as a "solid" surface.

At what falling speed can we consider the water as a 'solid' surface? The speed of sound in water?

• The speed of sound is higher in water than in air. You will die well before hitting Mach 1 (in air or water). I guess it is a question of inelastic collision, but on top of that is the question of what causes you to actually die, which is not a physics question. – Jon Custer Sep 15 '14 at 22:27
• The question of "at what impact speed does a liquid surface behave as a solid surface" is certainly physics though, and on-topic... as long as this is interpreted that way, it is on-topic (and, I would argue, interesting). – Kyle Oman Sep 15 '14 at 22:30
• Water can never be considered as a solid. Indeed, it is the other way around, at high speed solids behave like liquids. – CuriousOne Sep 16 '14 at 0:21
• right maybe I shouldn't have said that it behaves as a solid, but you get what I mean. The water does not move away quick enough. How can I get a velocity at which this happens? – SuperCiocia Sep 18 '14 at 22:03
• If the person hits the water incorrectly, they could die from falling 10 feet to the water. – LDC3 Nov 16 '14 at 16:43