Consider a U-tube filled with mercury except the 18-cm-high portion at the top, as shown in Fig. P3-128. The diameter of the right arm of the U-tube is D" 2 cm, and the diameter of the left arm is twice that. Oil with a specific gravity of 2.72 is poured into the left arm, forcing some mercury from the left arm into the right one. Determine the maximum amount of oil that can be added into the left arm. Oil SG = 2.12 18 cm D-2 cm 2D Mercury SG - 13.6