The characteristics of water

Hydrostatic pressure

Each molecule in any static fluid – due to gravitation – will exert pressure on the molecules below it.  As a consequence, inside the fluid there is a pressure exerted on any surface. This pressure inside a static liquid is called hydrostatic pressure and its value depends on the height of the fluid column and its specific density.

Bouyancy

It is an upward force exerted by a fluid that opposes the weight of an immersed object. This force derives from hydrostatic pressure.  As it is attested by Archimedes’ principle ’Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.’

The principle of effect/countereffect : Newton’s 3rd law of motion

This rule is very significant from the point of view of swimming. This law is as follows: ’    When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.’

Recalcitrance of matter

A force is exerted on any body moving in a static agent. This force is called the recalcitrance of matter, which depends on the shape, the density and the  speed of the moving body, and the largest cross section of the body perpendicular to the direction of its motion.

Resistance to block movement:

• The moving body needs to push forward or aside the particles of the agent.
• Friction between the moving body and the particles of the agent
• Vortex motion

All these resistances need to be defeated by the forward moving body. It has been proven by researchers that the whirls behind the body represent the most significant resistance.