I have to calculate the air pressure inside of an hot air balloon. After some searching I found out that I can use the ideal gas law: PV = nRT (from Wikipedia)
So to get the pressure in the balloon I would have to know n, which is the amount of gas in moles. For that amount I'm currently using the pressure (kg/m3) * the volume. So for the pressure I need the pressure which of course doesn't work.
Is there a way to calculate this? Right now I do know the normal air pressure (outside of the balloon) volume of the balloon etc. etc., but I can't know the weight of the amount of air in the balloon, because I use the pressure to calculate it. One thing to note is that it isn't an actual hot air balloon. It's just one made up from physics formulas in a program that calculates them every 0.1 seconds (for example) for me.
Is there some thing I'm missing?
Best Answer
Yes, the pressure is atmospheric, normally hot air balloons are not even sealed at the bottom. If it was sealed then it could have pressure higher than atmospheric, balanced by the wall elastic forces.