According to the first law of thermodynamics, the increase in the internal energy during any process involving a gas:
equals the heat input minus the work done on the gas
is independent of the work done on the gas
is independent of the heat input equals
the heat input plus the work done on the gas
equals the work done on the gas minus the heat input

The air in an automobile tire with a volume of 2.60 ft3 is at 70°f and 21 psig. determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant. the gas constant of air is ru = 53.34ft⋅lbflbm⋅r(1 psia144 lbf/ft2) = 0.3704 psia⋅ft3lbm⋅r the amount of air that must be added to raise the pressure is lbm