Heat and Thermodynamics

3.3 Work Done During Expansion of a Gas at Constant Pressure

Figure 3.4 shows some quantity of air enclosed in a cylinder under an airtight piston occupying the position A₁ B₁. Let the volume of the gas under the piston be v₁ and its pressure be p. Let the air expand at constant pressure forcing the piston to the position A₂ B₂. Let the mass of air now occupy the volume v₂. Let s be the area of the piston. Then the total force on the piston is s p. If d be the distance between the two positions of the piston, the work done in the expansion is spd.

 

 

Fig. 3.4 Schematic diagram for work done during expansion at constant pressure

 

But, sd is ...