Milk is an emulsion in which fat globules are dispersed within an aqueous solution that contains lactose, proteins, and minerals. Because the density of the fat is about 80 kg/m³ less than that of water, it tends to rise to the top and create a layer of cream. The mechanical breakup of the fat globules by homogenization stabilizes the milk against cream formation. The average diameter of the globules is reduced from about 2 μm in raw bovine milk to about 0.2 μm in homogenized milk (McClements, 2005, pp. 519–520). Compare the time required for all fat globules to rise to the top of a 20 cmtall carton of homogenized milk with that for raw milk. Can it be assumed that each size of globule reaches its terminal velocity immediately?