I can’t seem to wrap my head around the term pressure.
Vehicle tyres use air pressure, toilets faucets etc use pressure (presumably water pressure),
pressing onto something applies pressure, our blood has pressure, temperature is also affected by “pressure”.
I know there are various types of pressure, and I can’t think of any more examples at the moment, but my point is “pressure” sounds like a very arbitrary or vague umbrella term to me.
Help me make sense of it?
In: 3
imagine you get hit by a big ball with some speed on your back
you experience a push
what if instead of one ball you get hit by multiple smaller balls? if the smaller balls together where the same weight as the ball before and they hit you at the same time the push feels somewhat the same.
but if the hits are a bit spaced apart its just smaller balls hitting you repeatedly so easier to not fall back.
If you now start decreasing the ballsize/weight but also the amount of balls, while they are still flying with the same speed against your back you stop feeling the individual hits but just a general force.
You might also notice that if the balls where to keep hitting the same spot on your back instead of your entire back it feels more intense.
This motivates us to define this intensity now called pressure as some force over an area, which is of interest for gases and liquids as they are just “small balls” (atoms/molecules) flying around, colliding with each other and also its surrounding.
The reason why pressure, volume, temperature and particle number are related is following :
Temperature gets first defined as some unchanging property of a very big system. Then you find a condition when a given system has the same temperature as this very big system with set temperature. And then you find out that temperature is related with the average kinetic energy of the particles in your system of interest.
so pressure is what you experience as a wall of the container which is related to the speed of the balls (it gets more complicated as the balls dont have an uniform speed but a distribution with an average speed) while Temperature is related to the square of the average speed.
The ideal gas law pV ~ NT (proportional) that the energy needed to create the volume by pushing against the pressure p (energy is if the force is constant F* distance, where force is equal to pressure times area -> E= F*d=(p*A) * d = p * V) is proportional to the entire kinetic energy (temperature related to average kinetic energy times particle number)
Latest Answers