You exhale at the rate of 14 breaths a minute under normal conditions, each breath containing 0.50 L of air. You exhale against an external pressure of about 100 kPa.
a) Calculate the total amount of expansion work you do against the earth's atmosphere in a day.
b) If your typical intake of food is equivalent to 2500 nutritional calories (1 nutritional calorie = 4,184 J), what fraction of a day's energy consumption is this work by the lungs? [It's not this bad however, since the surroundings do work on the lungs when it contracts.]