An inverted piston-cylinder assembly fitted with a paddle-wheel contains air, initially at 20 lbf/in2 , 100°F and a volume of 0.33 ft3 . Energy in the amount of 1.5 Btu is transferred to the air by the paddle wheel. The piston is free to move without friction, and heat transfer with the surroundings can be ignored. Assuming an ideal gas model, determine the final temperature of the air, in °R.