Concept Theory | Pistons

Monday, 7 May 2018

1:14 PM

Consider a gas contained inside a cylinder sealed against a piston of mass .

As the piston pushes down, the pressure of the gas creates a reaction force .

Where  is the cross sectional area of the piston

 

The incremental work done on a gas by pushing a piston down by dy:

 

 

So

(If gas is compressed, , and , work is done on the gas)

(If gas expands, , and work is done by the gas)

 

 

(Work done on a gas equals the negative of the area under the PV curve)