Air that has a total mass of 0.1 lbm is confined inside a piston-cylinder system with a temperature of s5 °f and a pressure of 30 psi heat is added to the system while maintaining a constant pressure and as a result, during the process, the 6 in diameter piston rises a distance of 11.3 in. calculate (a) the work done per unit mass in [ft-lb/lbm] and (b) the change in specific internal energy in [btu/lbm] for this process.