Physics: Surface Tension, Hydrodynamics, Thermodynamics

Study Notes

The surface of a liquid acts like a stretched membrane due to the attraction between liquid molecules.
The force of attraction between surface molecules is parallel to the surface.
Resistance created by surface tension changes with the size of the object moving through it.
Moving an object through the surface of a fluid requires more effort than moving it underwater.

Hydrodynamics studies the properties and characteristics of fluids in motion.
There are two types of fluid movement: streamline (laminar) flow and turbulent flow.
Streamline flow occurs when fluid particles flow in a smooth path without crossing each other.
Turbulent flow involves fluid particles moving in erratic circles called eddies.
Movement against turbulent water creates significant resistance, similar to the sensation of moving your arm in a whirlpool.

Very Cold, Cold, Cool: Vasoconstriction (narrowing of blood vessels) and anesthesia (loss of sensation).
Tepid and Neutral: No loss of body heat or changes in core temperature or limb size (ideal temperature range for pool exercises).
Warm and Hot: Vasodilation (widening of blood vessels) and analgesia (pain relief).
Very Hot: Similar effects to warm and hot temperatures but may cause fatigue and overheating.

Specific heat is the amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius.
Water has a high specific heat capacity compared to air (four times that of air).
Water can absorb large amounts of heat without a significant temperature rise.
Water releases heat very slowly.
Hot packs can retain heat for over 30 minutes due to water's high specific heat.
Hot applications are used to improve circulation and reduce muscle spasms and tension.
Water temperature during exercise should be adjusted based on the exercise intensity.

Thermal conductivity is the rate of heat transfer through a substance by conduction.
Water has high thermal conductivity compared to air (25 times that of air).
The rate of heat transfer is directly proportional to thermal conductivity.
A larger temperature difference between the heat source and the skin will lead to faster heat transfer.
Extreme temperature differences can cause skin burns.