What property of water is responsible for the sensation of a "slap" when a belly flop is performed in a swimming pool?

The sensation of a "slap" experienced during a belly flop in a swimming pool is primarily due to the hydrogen bonding properties of water. Water molecules are held together by strong hydrogen bonds, which create a cohesive force within the liquid. This cohesion results in a relatively high surface tension, allowing the water surface to resist deformation to a certain extent.

When a person belly flops, the body strikes the water surface with a significant amount of force. The water molecules attempt to stay cohesive and are unable to easily part to accommodate the sudden, large surface area of the body entering the water. As a result, the surface tension is momentarily broken, and the energy from the impact is transferred to the water molecules. The abrupt stop and release of that energy, combined with the strong hydrogen bonds, generates the slap sensation on the skin.

The other properties listed, although interesting in their own right, do not directly explain the specific sensation experienced during a belly flop in the same way that hydrogen bonding does. Irregular expansion refers to the behavior of water when it freezes, capillary action describes how water moves through narrow spaces, and hydrophobic exclusion pertains to the way water interacts with non-polar substances. These concepts do not contribute to the phenomenon of a slap