Question

Glycerin is poured into an open U-shaped tube until the height in both sides is 18 cm . Ethyl alcohol is then poured into one arm until the height of the alcohol column is 18 cm . The two liquids do not mix.What is the difference in height between the top surface of the glycerin and the top surface of the alcohol?

Answer 1

Density of:
alcohol, ethyl (grain) - 789.2
glycerin - 1260

The pressure at the border between the alcohol and the glycerol is p(a) = ρgh
p(a) = 789.2*g*0.18
at the same height on the other side is the pressure equally large. And this pressure is
p(g) = 1260*g*s ( s = height of glycerin above the alcohol/glycerin border level)
p(g) = p(a)
1260s = 789,2*0.18
s = 0.112m

> the difference in height between the top surface of the glycerin and the top surface of the alcohol
0.18m - 0.112m
The difference between h and s = 0.068 m = 6.8 cm,
which difference in height between the alcohol and the glycerin.