A hollow plastic spherical bobber of mass 0.005 kg and volume 50 cm3 floats on the surface of a lake. The bobber supports a submersed fishhook and 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, that 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.