- Usually, a U-tube is used to compare and measure the density of liquids.
- The density of the 2 liquids is related by the equation:
h1ρ1 = h2ρ2
Example:
Figure above shows a U-tube filled with water and liquid P. Liquid P is insoluble in water. Given that the density of water is 1000kg/m³, find the density of liquid P.
Answer:
h1 = 10cm
h2 = 12 cm
ρ1 = 1000kg/m³
ρ2 = ?
h1ρ1 = h2ρ2
(10)(1000)=(12) ρ2
ρ2 = 10000/12
=833kgm−3
The density of liquid P = 833 kg/m³
Example:
The diagram shows a U-tube filled with two types of liquid, X and Y which are not mixable. If the density of liquid X and liquid Y are 1200 kg/m³ and 800 kg/m³ respectively, find the value of h.
Answer:
h1 = 10cm
h2 = h
ρ1 = 800kg/m³
ρ2 = 1200kg/m³
h1ρ1 = h2ρ2
(10)(1200)=h(800)
h= 12000/800
h =15cm