1-ft3 of air is contained in a spring-loaded piston-cylinder device. the spring constant is 6lbf/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.

On a hot saturday morning while people are working inside, the air conditioner keeps the temperature inside the building at 22degreesc. at noon the air conditioner is turned off, and the people go home. the temperature outside is a constant 33degreesc for the rest of the afternoon. if the time constant for the building is 4 hr, what will be the temperature inside the building at 4 : 00 font size decreased by 2 upper p . font size decreased by 2 upper m .? at 6 : 00 font size decreased by 2 upper p . font size decreased by 2 upper m .? when will the temperature inside the building reach 24degreesc? 324281