1) The two-story office building has 36,000 ft³ of office space. Due to cracks around windows and doors, the air leaks in on the windward side of the building and exits on the leeward side. Tests were conducted on the building for energy efficiency when the outdoor temperature was 15°F. The inside was at 70°F. The infiltration rate due to cracks was 75 ft³/min and infiltration due to door openings was 50 ft³/min.

a) What is the volumetric flow rate of air exiting the building assuming steady state,air as an ideal gas and no significant pressure difference between the inside and outside of the building?

b)Determine the number of building air volume changes per hour.

c)If you need to meet the CDC guidance for airborne contaminant removal at 2 ACH, do you need to change the ventilation for the building?

2) A 12 oz. mug of coffee contains 200 mg of caffeine. Caffeine is eliminated from the body at a rate of dmcaf/dt = -0.116mcaf, where mcaf is the mass of caffeine in the body in mg and t is in hours. After you chug a 12 oz. coffee, how long will it take for the caffeine in your body to drop to 100 mg? You drink one mug at 6 am and another at 2 pm.

a) Plot the caffeine content of your body as a function of time for a 24 hour period.

b) What is the level of caffeine in your body at 11 pm? If you are having trouble falling asleep at 11 pm, would it help to cut out the second coffee?