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 trees ?

Explanation

Using ascent formula, the height to which the sap will rise due to capillarity action is `h=(2T cos 0^(@))/(pgr)`
`=(2(7.28 xx 10^(-2)))/(10^(3) xx 9.8 xx 2.5 xx 10^(-5)) approx 0.6 m`
0.6 m is the maximum height upto which the sap rises due to the surface tension. Actually many trees have heights greater than this, capillary action alone is not responsible for the rise of water in all trees.