Halliday, Resnick & Walker — Fluids: Problem 42

42 Lurking alligators. An alligator waits for prey by floating with only the top of its head exposed, so that the prey cannot easily see it. One way it can adjust the extent of sinking is by controlling the size of its lungs. Another way may be by swallowing stones (gastrolithes) that then reside in the stomach. Figure 14-38 shows a highly simplified model (a “rhombohedron gater”) of mass 145 kg that roams with its head partially exposed. The top head surface has area 0.15 m². If the alligator were to swallow stones with a total mass of 1.0% of its body mass (a typical amount), how far would it sink?