Question

If surface tension of water is 0.07N/m the weight of water supported in a capillary tube of radius 0.1 mm

Can someone please explain why we need to use mg= 2× pi×r×Surface tension

Answer 1

Given :

surface tension of water is 0.07N/m

Radius of capillary tube is 0.1 mm

To Find :

weight of water in capillary tube .

Solution :

•Capillary tube is a long tube with narrow base

• When a capillary is dipped normally or at any angle in liquid . It is found that liquid level either rises or descends relative to surrounding level of liquid , such phenomenon is known as capillary action .

•Also,

h = 2T/pgR

•where h is rise in level of liquid

T is surface tension

p is density of liquid

g is acceleration due to gravity

h = 2 ×0.07/(1000×10×10^-⁴)

h = 0.14 m = 14 cm

•Volume of water = πr²h

Volume of water = 22×10^-⁴×14/7

Volume of water = 44 × 10^-⁴ cm³

•Weigth of water = pv = 44×10^-⁴ g