Pulley and Vacuum

[Ryan Fang 1D]

I'm slightly confused about the pulley and vacuum system that Dr.Lavelle discussed in lecture. He mentioned that work is done by a system expanding into a vacuum if mass from the pulley is removed or something along those lines. Can someone explain why this is so? Thank you!

[Lucian1F]

If you imagine a piston thats controlled by a weight and that weight is slowly removed, then the system will slowly expand and do work

[Isaiah Little 1A 14B]

Without the weight pulley controlling the gas's volume, the gas would expand throughout the container because of the positive pressure it exerts against the vacuum. Adding weight to the pulley will counteract the pressure exerted by the gas, compressing said gas in the container -- whereas removing the weight will allow the gas to exert a higher net force on the wall that separates the vacuum from the gas, allowing the gas to do work.