A U-tube contains water and methylated spirit separated by mercury. The mercury columns in the two a

Question

A U-tube contains water and methylated spirit separated by mercury. The mercury columns in the two arms are perfectly in level with $10.0	ext{ cm}$ of water in one arm and $12.5	ext{ cm}$ of spirit in the other. What is the specific gravity of the spirit?

Professor PC Thomas Classes · Answer

Since the mercury levels are equal, the pressure exerted by the water column equals the pressure exerted by the spirit column. $ho_w g h_w = ho_s g h_s \implies 	ext{Specific gravity} = \frac{ho_s}{ho_w} = \frac{h_w}{h_s} = \frac{10.0}{12.5} = 0.8$.