Calculating Liquid Height Difference in U-Tube | Fluid Mechanics Homework

[bennyq]

Homework Statement

One hundred millilitres of water is poured into a U-tube that has a cross-sectional area of 1 cm2. Then 100 millilitres of oil, with a density 80% that of water, is poured down one side of the U-tube so that the oil floats on the water. Find the difference in height of the liquid surfaces on the two sides of the U-tube.

Homework Equations

P=gph

The Attempt at a Solution

Just struggling to get started, i know that on either side that at a certain point the pressures are equal.
Just a pointer to get going would be great..

 

[Chestermiller]

Homework Statement

One hundred millilitres of water is poured into a U-tube that has a cross-sectional area of 1 cm2. Then 100 millilitres of oil, with a density 80% that of water, is poured down one side of the U-tube so that the oil floats on the water. Find the difference in height of the liquid surfaces on the two sides of the U-tube.

Homework Equations

P=gph

The Attempt at a Solution

Just struggling to get started, i know that on either side that at a certain point the pressures are equal.
Just a pointer to get going would be great..

Match them up at the bottom of the U.

Chet

 

[bennyq]

in my sketch, i have Pa = LHS p(oil)gh = RHS p(water)gL .. g cancels our but i have two unknowns..which is the different heights of each column?

 

[Chestermiller]

in my sketch, i have Pa = LHS p(oil)gh = RHS p(water)gL .. g cancels our but i have two unknowns..which is the different heights of each column?

If h is the height of the oil above the oil-water interface, and L is the height of the water above the oil-water interface, the h = 100 cm.

Chet

 

[bennyq]

ah okay, thank you chet