Having not done fluid mechanics the [itex]F_b[/itex] may indicate to me the buoyancy or something? Maybe V is viscosity?
Is your p for momentum, or really a rho, for density? if so, the RHS of your equation can become mg, if v is volume.
But yea, really, this should be in Introductory Physics or something, not precalc math. And why does your title refer to arildno, he's not the only person who tries to help you know :P