pressure and temperature

Temperature
? Though we all have a feel for temperature (‘like when we are feeling hot’); in the context of TD temperature is technical term with ‘deep meaning’.
? As we know (from a commons sense perspective) that temperature is a measure of the ‘intensity of heat’. ‘Heat flows’ (energy is transferred as heat) from a body at higher temperature to one at lower temperature. (Like pressure is a measure of the intensity of ‘force applied by matter’? matter (for now a fluid) flows from region of higher pressure to lower pressure).
? That implies (to reiterate the obvious!) if I connect two bodies? (A)-one weighing 100kg at 10?C and the other (B) weighing 1 kg at 500?C, then the ‘heat will flow’ from the hotter body to the colder body (i.e. the weight or volume of the body does not matter).
? But, temperature comes in two important ‘technical’ contexts in TD:
1? it is a measure of the average kinetic energy (or velocity) of the constituent entities (say molecules)
2? it is the parameter which determines the distribution of species (say molecules) across various energy states available.
Temperature as a parameter determining the distribution of species across energy levels
? Let us consider various energy levels available for molecules in a system to be promoted to.
? At low temperatures the lower energy levels are expected to be populated more, as compared to higher energy levels. As we heat the system, more and more molecules will be promoted to higher energy levels.


Pressure:
? Pressure* is force per unit area (usually exerted by a fluid on a wall**).
? It is the momentum transferred (say on a flat wall by the molecules of a gas) per unit area, per unit time. (In the case of gas molecules it is the average momentum transferred per unit area per unit time on to the flat wall).
? P = momentum transferred/area/time.
? Pressure is related to momentum, while temperature is related to kinetic energy.






* ‘Normal’ pressure is also referred to as hydrostatic pressure.
** Other agents causing pressure could be radiation, macroscopic objects impinging on a wall, etc.