Awooden cylinder of length l and cross-sectional area a is partially submerged in a liquid with the axis of the cylinder oriented straight up and down. the density of the liquid is rhol. if the length of the cylinder that is below the surface of the liquid is d, what is the buoyant force that the liquid exerts on the cylinder? (ignore the small buoyant force exerted by the air on the part of the cylinder above the surface of the liquid.)