The sap in trees, which consists mainly of water in summer, rises in a system of capillaries of radius `r = 2.5 xx 10^(-5) m.` The surface tension of sap is `T =7.28 xx 10^(-2) Nm^(-1)` and the angle of contact is `0^@.` Does surface tension alone ac count for the supply of water to the top of all tress ?

Explanation

The maximum height to which sap can rise in a tree through caplilarity action is given by `h = (2T cos theta)/(r rho g) = (2xx(7.28 xx 10^(-2)) xx cos 0^@)/((2.5 xx 10^(-5) xx 10^3 xx 9.8)) ~~ 0.6 m`
Since many trees have height more then 0.6 m therefore, rise of sap through capillarity action alone in big trees is not possible.