Question

A liquid is used to make a mercury-type barometer. The barometer is intended for spacefaring astronauts. At the surface of the earth, the column of liquid rises to a height of 2185 mm, but on the surface of Planet X, where the acceleration due to gravity is one-fourth of its value on the earth, the column rises to only 725 mm. Find the (a) the density of the liquid, (b) the atmospheric pressure at the surface of Planet X.

Answer 1

Height will be proportional to g, and pressure, and inversely to density.

Height=k g * P/density

At Earth
2185mm=k g 101.3kPa/density
at X
725mm=k *g/4 * PressureX/density

Divide the top equation into the bottom..

725/2185=1/4 * PressureX that gives you pressurex

Now for density, you know the density of mercury, and how far it goes up at atmospheric pressure, so wouldn't that tell you the density of the substance is 760/2185= densityX/density mercury?