Question 21:
easy
A U-tube contains water and methylated spirit separated by mercury. The mercury columns in the two arms are in level with \(12\text{ cm}\) of water in one arm and \(15\text{ cm}\) of spirit in other. The specific gravity of spirit is
At the interface level, the pressure on both sides must be equal: \(h_w \rho_w g = h_s \rho_s g\). Thus, \(\rho_s / \rho_w = h_w / h_s = 12 / 15 = 0.8\).