Suppose you have a cylinder filled with an ideal gas and a piston on top which can slide up and down. If you want to get work done using isobaric, isothermic or any other process (other than adiabatic) you apply heat. Makes sense.
But in adiabatic process, you can't apply heat. So do you shout to the gas "Hey gas, lose some internal energy and do work!" or what do you do exactly to?
I have two ideas: one is that you pull the piston upwards, but that makes no sense to me because then I'm the one doing work, not the gas
The other is that I reduce pressure on the piston, and then the volume will increase. But once again I'm applying some sort of work to change the pressure so... is the gas doing anything really?