Hydrostatics – Benzene poured into uniform U shaped tube with water

1. The problem statement, all variables and given/known data
A uniform glass tube is bent into a U shape. Water is poured into the tube till it stands 10cm in each tube.

Benzene (sp gr = 0.879) is then slowly added to the tube on the left side until the water rises 4cm on the right.

What length is the column of benzene when the situation is reached? (Water and benzene don’t mix).

2. Relevant equations
(pgh)1 = (pgh)2

3. The attempt at a solution

I know that sp gr is the ratio between the density of benzene and water (p1/p2). Using the relevant equation I have to solve for h1 (1 being benzene).

h1 = h2/0.879

The book gives the answer and says h2 is 8cm. I am having trouble finding out how it equals 8cm.

You’d think that it would be 14cm since it was initially at 10cm and the right side rises 4cm. This problem is making zero sense.

Any info would be helpful. I’m just starting on fluids in this class. Thanks!


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