A piston-cylinder assembly contains 0.3 lb of propane. The propane expands from an initial state where p₁ = 60 lbf/in.² and T₁ = 30°F to a final state where p2 = 10 lbf/in.² During the process, the pressure and specific volume are related by pv² = constant. Determine the energy transfer by work, in Btu.

A piston-cylinder assembly contains 0.3 lb of propane. The propane expands from an initial state where p₁ = 60 lbf/in.² and T₁ = 30°F to a final state where p2 = 10 lbf/in.² During the process, the pressure and specific volume are related by pv² = constant. Determine the energy transfer by work, in Btu.