Question

The sap in tree rises in a system of capillaries of radius $2.5\times {10}^{-5}m$. The surface tension of sap is $7.28\times {10}^{-2}N{m}^{-1}$ and the angle of contact is $0^o$. The maximum height to which sap can rise in a tree through capillarity action is (${\rho }_{sap}={10}^{3}kg{m}^{-3}$)

• A. 0.21 m
• B. 0.59 m
• C. 0.87 m
• D. 0.91 m

Answer 1

The correct option is B 0.59 m

Here, $r=2.3\times {10}^{-5}m,$

$S=7.28\times {10}^{-2}N{m}^{-1}$

Angle of contact, $\theta =0^o,$

$\rho ={10}^{3}kg{m}^{-3}$

The maximum height to which the sap can rise by capillary action is,

$h=\frac{2Scos\theta }{r\rho g}=\frac{2\times 7.28\times {10}^{-2}\times cos{0}^o}{2.5\times {10}^{-5}\times {10}^3\times 9.8}=0.59m$