Question

Glycerin is poured into an open U-shaped tube until the height in both sides is 34 cm. Ethyl alcohol is then poured into one arm until the height of the alcohol column is 20 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? I keep getting 12.6 cm as the answer but it is wrong. please help!!

Answer 1

Your process till height = 12.6 cm is correct.

Now read the question one more time.

We need the difference in height between to top surface of glycerin and top surface of the alcohol

given that height of ethyl alcohol = 20 cm

we got h = 12.6 cm = that is height of glycerin in other arm

Now difference between both heights will be = 20 - 12.6 = 7.4 cm

Please Let me know if you need anything else.

Please Upvote.

At same hight

Pressure in glycerin side = pressure in alcohol side

Pg = Pa

rho_g*g*hg = pho_a*g*ha

ha = 20 cm

hg = 20*790/1260 = 12.54 cm