Oil and water do not mix due to their incompatible molecular interactions. Imagine a U-shaped tube with a constant cross-sectional area of 1 cm2 that holds enough water (1000 kg/m3) that the level on each side is in the straight part of the tube (figure left). Now 10.7 mL of oil (700 kg/m3) is added and reaches equilibrium as shown. How high did the water level rise in cm? The pressure at the interface of two fluids (blue/yellow) will be the same for each fluid.
