As shown, a weight sits on a piston of diameter D₁. The piston rides on a reservoir of oil of depth h₁ and specific gravity SG. The reservoir is connected to a round tube of diameter D₂ and oil rises in the tube to height h₂. The oil in the tube is open to atmosphere. Derive an equation for the height h₂ in terms of the weight W of the load and other relevant variables. Neglect the weight of the piston.