In this experiment, physical science students measured the mass of several soda cans, measured the mass and volume of water displaced when these cans were placed in water, and determined whether these cans sank or floated in water. Then, the students plotted graphs of the mass of displaced water versus the volume of displaced water, the mass of the soda cans versus the mass of displaced water, and the mass of the soda cans versus the volume of displaced water. The slope of the first graph provides the density of the displaced liquid (water). The second graph shows that the mass of displaced water equals the mass of the soda can for the floating cans (Archimedes’ principle), but the mass of displaced water is less than the soda can’s mass for the sinking cans. The slope of the floating cans in the third graph represents the density of the displaced liquid and the average volume for the sinking cans yields an average volume for all of the cans. Using this average volume for the soda cans, students calculate the density of each soda can and determine that objects whose densities are less than the liquid will float in it while objects whose densities are greater than the liquid will sink in it (the principle of flotation).
Supplement
A sheet of instructions for students; An answer key to the student questions; Notes for the instructor
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