I'm extremely confused about work done on a gas. So if you look at the system pictured,
From what I've read online, the net work done, which is equal to the work done by the objects, is equal to the pressure times the change in volume, $W=p\,\Delta V$.
But I'm confused on is how can this be true. Why wouldn't the net work done on the gas be equal to the work done on both the gas and the atmosphere, which is also applying a force on the gas? It doesn't make sense that the net work being done on the gas is equal to only the work being done by the objects.
Thanks, I hope I explained my issue correctly here.