Question:
The sap in trees, which consists mainly of water in summer, rises in a system of capillaries of radius r = 2.5 × 10-5 m. The surface tension of sap is T = 7.28 × 10-2 N/m and the angle of contact is 0o. Does surface tension alone account for the supply of water to the top of all tress?
Solution:
Radius, r = 2.5 × 10-5 m
Surface tension, T = 7.28 × 10-2 N/m
Angle of contact, θ = 0o
Density, ρ = 103 kg/m3
The maximum height h is given as:
$h=\frac{2 S \cos \theta}{r \rho g}$
Substituting the values we get, h = 0.6 m