PHYSICS 3B Study Guide - Final Guide: Volumetric Flow Rate, Buoyancy, Internal Resistance
23 Nov 2015
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Fluids (8 points: to serve its function, a child"s inflatable life belt must keep at least 15% of the wearer"s body volume (head and shoulders) above water. Suppose the left belt has a volume of 3. 80 liters, and is fully submerged. Assume the average density of a human body is 950 kg/m3. You may neglect the density of the air in the life belt. (4 points) The volume of the child is vchild = m/ , where m is the child"s mass (which we want to find) and = 950 kg/m3 as given. The volume submerged is the volume of the belt vbelt = 3. 80 liters = 3. 80 10-3 m3, plus. 85% of the child"s volume, 0. 85 vchild = 0. 85 (m/ ): The buoyant force will be the weight of this volume of water: fb = water g vsub, and this must equal the child"s weight: fb = water g (0. 85 m/ +vbelt) = m g.
