Practice Problem 13.1 Let's begin with a simple calculation of the weight of air using density. Find the mass of air and its weight in a living room that has a 3.5m x 4.0m floor and a ceiling 2.7 m high. What are the mass and weight of an equal volume of water? Figure 1 h of 1 2 Air has a density of p = 1.2 kg/m. The mass of the air in the room is The weight of the air is The weight is V=lxwxh= (3.5m) (4.0m) (2.7m) = 37.8m w = mg = (45.36kg) (9.8 m/s2) = 444.5N The density of water is p = 1.0 10 kg/m. Thus, the mass of a volume of water that would fill the room is m = pV (1000 kg/m) (37.8m) = 3.78 x 10kg m = pV = (1.2 kg/m) (37.8m) = 45.36kg w = (3.78 x 10kg) (9.8 m/s) = 3.704 105N REFLECT The weight of the air is about 99.9 lb. Does it surprise you that a roomful of air weighs this much? But the weight of the same volume of water is about 8.33x104 lb, or 41.6 tons! This much weight would certainly collapse the floor of an ordinary house. 14 Part A - Practice Problem: What volume of water would have a mass equal to the mass of air in the room? Express your answer in liters to two significant figures. Submit My Answers Give Up ? Incorrect; Try Again; 4 attempts remaining