What would happen if you hit a body of water( say an ocean) at the terminal velocity of a person of avg proportions without any special clothing on..just like a jumpsuit? (how would it change for Feet first/head first/belly flop/at an angle etc?)
At less than terminal velocity, you might want to consider hitting concrete instead if you can. It compresses. Water on the other hand, has a very low compressability at such speeds. There is a trick people do for diving very high heights. Drop a fairly heavy object before you to break the surface tension. But ya, at terminal velocity your probably going to be killed no matter what you hit.
A human will die at hitting the water at a minimum of 60 mph. Water has a very strong surface tension, trust me I've hit it at about 40 mph, it hurts like hell.
It's nowt to do with the surface tension and all to do with inertia - basically shifting the water out of the way fast enough - 'added mass' is the term when shifting liquids. If you can minimise the amount to be shifted, and ensure that it is struck by a non-vital organ (i.e hands and not head) then you increase your survival chances. That's what a high diver would do. I doubt whether you'd survive a 200 mph impact under any circumstances.
Yes, when they hit 30-50 ft of snow or in similar circumstances. Basicly serious inguries start at a=20g and practically no one survives beyong 30g acceleration. One can easily calculate required braking distance s=v^{2}/2a for any velocity v and maximal braking acceleration a. For 200 mph and a=25g you get minimal braking distance to be about 17 m (~50 ft).