How to visualise pressure
I'm back after a year or so, this one is not about pressure in life, career or anything like that, this is a blog about pressure in the real sense, like technical meaning of pressure cause I have struggled a lot over the past 8-9 months trying to visualise and get an understanding of what pressure means.
It's defined as force upon area the amount of force applied perpendicular to the surface of an object per unit area but this definition is kinda vague and it does not make sense to me atleast. I get that the molecules at interacting with each other and with the walls of the of the system we are observing (imaginary in some cases), we are using that wall as a reference for the perpendicular and the area for the force calculation.
Pressure is the momentum transferred per area per unit of time, this is a definition that one of my profs gave and this makes more sense than the other one but this is still hard visualise what pressure as a quantity is considering it affects volume and temperature which are both not as hard to visualise. Volume is pretty straight forward and temperature is the average kinetic energy that the body under observation has at the time of measurement. Both these quantities make seem quite mechanical at the molecular level. volume is the total space available within the universe for the molecules of the body to expand/wander into and temperature is the average kinetic energy that the molecules of the said body has. Looking at these quantites as such kinda gives us a idea how pressure, temperature and volume are related.
Our person of the moment Pressure, is a tougher nut to crack because as cliche as it sounds, it is something which is much easier to feel than to understand on paper. When it's said that pressure is kept constant what does that even mean? It means that the amount of momentum being transferred is constant. i.e. the interaction of the molecules with the wall stays the same irrespective of the what happens to the wall itself, whether it becomes smaller, larger, orientation changes, the momentum being transferred stays the same, the interaction stays the same. The pressure cooker is what helped me understand this more like visualise it.
We need the temperature inside the cooker to reach higher temperature cause that creates a potential difference for the energy to move into the water which is at a lower temperature which in turn cooks the food by transferring the energy forward. To facilitate the said transfer of energy, the volume is kept constant but the energy in the form of heat is supplied to the cooker which increase the kinetic energy of the molecules present in them but the space for the molecules to move around isn't increasing which leads to the increase in the interaction of the molecules with the walls which is inferred as the pressure increasing.
These higher energy molecules come in contact with the food in the cooker and transfer the energy they have into the food as they have lesser energy in comparison and the food gets cooked.
This is my rudimentary understanding from whatever literature I have read and tried to apply my own deduction, please correct me if I am on the wrong track.
Peace.