1-ft of air is contained in a spring-loaded piston-cylinder device. The spring constant is 61bf/in, and the piston diameter is 12 in. When no force is exerted by the spring on the piston, the state of the air is 250 psia and 450°F. This device is now cooled until the volume is one-third its original size. Determine the change in the specific internal energy and enthalpy of the air.