A volume of 20 cu ft of air at a pressure of 50 psig is heated and expanded to 30 cu ft and 40 psig. Find the change in the energy of air in joules.

39,047.6 Joules

Explanation:

Step 1: identify the given parameters

Initial Volume of gas (V₁) = 20 Ft³

Final Volume of Gas (V₂) = 30 Ft³

Initial Pressure of Gas (P₁) = 50 psig

Final Pressure of Gas (P₂) = 40 psig

Step 2: Calculate Energy change of the gas

E = ΔPV

E = P₂V₂ - P₁V₁

E = (40*30) - (50*20)

E = 1200 - 1000

E = 200 Ft³. Psig

Convert to Joules

1 Ft³. Psig = 195.238

200 Ft³. Psig = ?

= 39,047.6 Joules