Isochoric process and Isobaric process

고등학교 물리시간에 배우는 매우 간단한 내용이지만 기록해두는 목적으로 올려봅니다.

 

$$W=F\times S$$

$$P=\frac{F}{A}$$

$$W=PAS=PV$$

 

For isobaric process which means constant pressure $dP=const$ 

 

$$\delta W=PdV+VdP$$

$$\delta W=PdV$$

 

Now we can see the familiar form of work equation.

However, for isochoric process which means constant volume $dV=const$

 

$$\delta W=PdV+VdP$$

$$\delta W=VdP$$

 

 

Imagine the steam train. If piston engine remains constant, they can't do work.

That's the reason why we usually use $W=PdV$.