Hello people, first of all thanks to all who reads this and attempts this problem or more or less helps me see the underlying principles. A little background...i am a first semester 23 yr. old summer school physics student who has an exam tomorrow, monday night. The exam covers buoyancy, fluids, density& pressure and rotational kinetic energy. Good stuff i know....here is a problem from an old exam last semester. It reads exactly..... A 1.0 kg hollow ball of radius .10 m, filled with air, is released from rest at the bottom of a 2.0 m deep pool of water. How high above the surface of the water does the ball rise? Neglect all frictional effects and the changing force on the ball when it is partially submerged. Volume of a sphere = 4/3 pi r^3; rho_air (denisty of air) = 1.29 kg/m^3; rho_water (density of water) = 1000 kg/m^3. I am on a time crunch this morning so i'll try to condense as much as I know about this problem as I can with the time constraints i am on and will come back around 5 and read what people have to say. I really want to understand what actually is happening, because that is where physics is difficult for me. This problem is an application to what Bernouli and Archimede's studied. I believe the height value i'm looking for is located in the gravitational potential energy term of Bernouli's equation, rho*g*y (rho = density). The velocity terms in the equation drop out because the ball starts from rest and finishes at rest. If anything i'm saying is incorrect or if my thinking is skewd, please let me know. Thanks....i gotta go work a few hours then i'll be back :) peace.