© Copyright, Department of Physics, University of Illinois at Urbana-Champaign


A hollow plastic spherical bobber of mass 0.005 kg and volume of 50 cm3 floats on the surface of a lake supporting a submersed fishhook and a bait with a combined mass of 0.01 kg and a combined volume of 2 cm3. The density of water is 0.001 kg/cm3.

If a fish grabs the bait, find the minimum downward force, Ffish, it must exert to pull the bobber completely under the surface of the water. You may assume that the apparent weight of the fish is zero, and the fishing line is completely slack.

F = N