Question

Air having a pressure of 40 psig and a volume of 8 cu ft expands isothermally to a pressure of 10 psig. Find the external work performed during the expansion.

Answer 1

357.6 lb-ft

Step-by-step explanation:

V = Volume = 8 ft³

dP = Change in pressure = (40-10) = 30 psig

Work done is given by

`W=VdP\\\Rightarrow W=8* (40-10)\\\Rightarrow W=240\ psig.ft^3`

`30\ psig=44.7\ psi\\\Rightarrow 1\ psi=(30)/(44.7)`

So, converting to ft-lb

`(240)/((30)/(44.7))=357.6\ lb-ft`

The external work performed during the expansion is 357.6 lb-ft