"What is the least amount work you must issue onto a silver ingot with a mass of 38 kg at 26 meters depth to bring it to the surface?"
I'm not sure how to do this one. Surely it depends on the volume of the ingot, right? Archimedes' principle says that the buoyancy of an object is its volume times the density of the fluid times the gravitational constant. We only have two of those, so I can't find the lifting force. This is how my formula looks like (Since the force is constant across all depths):
$F_L = $Lifting force
Force required $= mg - F_L$
Force required $= 38kg * g - (1000kg/m^3 * g * V)$
Work $=$ Force required * distance
Work $= 38kg * g - (1000kg/m^3 * g * V) * 26m$
Volume is still unknown, so how do I solve this one?