Algodoo

On the macro scale, surface tension plays almost no role in physics. belly flops hurt simply because your belly is being stopped near instantly, the same reason why a car crash causes damage.

s c i e n c e

UnityDogGaming04 is correct, but there's a reason why your body stops so quickly when falling into water. The reason why belly flops hurt so much is because water (and most other liquids) cannot be compressed. Therefore, it does not provide a cushion effect like air or other gases would. Your falling body hits the water, and because of the water's mass, does not get displaced very quickly by your body. So, for a very brief period of time (a few milliseconds) your belly gets compressed very quickly, sort of like getting hit in your stomach by a professional boxer (ouch!).

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