A column carries 5400 lbs. of load and is supported on a spread footing. The
footing rests on coarse sand. Design the smallest square footing (to the next 3”
increment) that will safely carry the column load. The footing will be 1'-9" deep
and will be constructed of cast-in-place concrete. Note: Concrete weights 150
lbs/cubic foot. Show all work.

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.