G When a cake is removed from an oven and placed on a kitchen counter, its temperature is measured at 300◦F. Three minutes later its temperature is 250◦F. Write the initial value problem describing the change in the temperature of the cake, if the temperature of the kitchen is 70◦F.

Air initially at 0.75 bar, 1000 k, and occupying a volume of 0.12 m^3 undergoes two processes. process 1-2: the air is compressed isothermally until the volume is halved. process 2-3: the air undergoes a constant pressure process until the volume is halved again. assume ideal gas behavior. a) determine the mass of the air, in kg. b) the work and the heat transfer for each of the two processes, in kj. (100 kj = 1 bar . m^3)