I'm a big fan of the PhET simulations.
But I'm puzzled by one aspect of the "Gas Properties" simulation.
If you open the simulation and squirt some gas (maybe 100 particles) into the chamber, the particles bounce around nicely. If you then compress the gas, the pressure and temperature increase as one might expect.
But reset it, squirt some gas in, and expand the chamber. The pressure drops, but the temperature remains the same. I was hoping for adiabatic cooling, but all I got was isothermal (and adiabatic!) expansion.
My thoughts? I want the temperature to drop: particles bouncing off a receding wall should recoil with reduced speed. And an expansion shouldn't be isothermal unless heat is added.
The good people at PhET assure me this is what's supposed to happen. But sometimes I'm just too thick to get it.
Educate me, experts!