2006-12-19 18:21:22 · 11 answers · asked by damodharan c 1 in Science & Mathematics ➔ Botany
Capillary action, capillarity, or capillary motion is the ability of a substance (the standard reference is to a tube in plants but can be seen readily with porous paper) to draw a substance up against gravity. It occurs when the adhesive intermolecular forces between the liquid and a substance are stronger than the cohesive intermolecular forces inside the liquid. The effect causes a concave meniscus to form where the substance is touching a vertical surface. The same effect is what causes porous materials to soak up liquids.
A common apparatus used to demonstrate capillary action is the capillary tube. When the lower end of a vertical glass tube is placed in a liquid such as water, a concave meniscus forms. Surface tension pulls the liquid column up until there is a sufficient weight of liquid for gravitational forces to overcome the intermolecular forces. The weight of the liquid column is proportional to the square of the tube's diameter, but the contact area between the liquid and the tube is proportional only to the diameter of the tube, so a narrow tube will draw a liquid column higher than a wide tube. For example, a glass capillary tube 0.5 mm in diameter will lift a theoretical 2.8 cm column of water. Actual observations show shorter total distances.
With some pairs of materials, such as mercury and glass, the interatomic forces within the liquid exceed those between the solid and the liquid, so a convex meniscus forms and capillary action works in reverse.
2006-12-19 18:24:34 · answer #1 · answered by Mysterious 3 · 0⤊ 0⤋
Water moves up a tree in three ways. First is diffusion, water moves from the soil into the roots because there is less in the roots than in the soil. Water is pushed up slightly by this process. In the roots water travels through tubes made up of cells of the xylem. Second, within the xylem the properties of water allow the water to move up the tree's body. First is adhesion, the water droplets cling to the side of the surface they are against, the second is cohesion, each water molecule sticks to the next due to the fact that they are polar in nature, the oxygen and hydrogen atoms each carrying a slight charge attracting the other of a like molecule. Third is that at the leaves of the tree water is constantly evaporating, moreso when it is hot, and so this in effect pulls the water up from the ground through the xylem because of the cohesive properties of water. All these things combined allow water to climb the greatest heights of the mightiest tree.
2006-12-19 18:38:11 · answer #2 · answered by Anonymous · 0⤊ 0⤋
From root hair to xylem vessel water moves by
Absorption
Thin film of water on soil particle is absorbed by root hair cell. Osmosis
Soil water is passed through the semipermeable membrane of root hairs since water concentration is lower in cell sap.
Active transport
This requires energy created by respiration. Even when the water is more in plant this absorption takes place.
From xylem vessel to great heights of plants
Capillary action
Just as in capillary tube
Transpirational pull.
Its a suction pressure developed in plants due to the evaporation of water vapour from stomata.
2006-12-19 20:56:32 · answer #3 · answered by grefriend 2 · 0⤊ 0⤋
In plants water in conducted through the xylem vessels.. the xylem vessels are very thin and the water raises in them through capillary action just as water raises in the capillary tube... This capillary force is responsible for the water raising in the plants and to get stored in great heights...
2006-12-19 18:33:15 · answer #4 · answered by Eshwar 3 · 0⤊ 0⤋
The combined action of transpiration, capillary action and the cohesion and adhesion of the water molecules help it to be conducted up to great heights
2006-12-21 03:51:43 · answer #5 · answered by Anonymous · 0⤊ 0⤋
capillary action do not actually guarantee since gravity is already against the water rising at a significant height. osmosis can. transpiration can also be of good use. plants use the concept of evaporation in transpiration.
2006-12-20 02:12:09 · answer #6 · answered by glen_tigger 2 · 0⤊ 0⤋
im not so sure about this but il tel you what i tnk. as you know soil absorbs water and everything has its own limitations including ground absorption. So when the ground cant aymore absorb all the water then it would not anymore stay on the ground. It rises up because there are no more rooms in the ground for water to stay.
2006-12-19 18:26:22 · answer #7 · answered by jen 2 · 0⤊ 1⤋
Basically, capillary action, with some unique twists related to trees, ie transpiration:
http://biomechanics.bio.uci.edu/_html/nh_biomech/trees/trees.htm
2006-12-19 18:28:45 · answer #8 · answered by EQ 6 · 0⤊ 0⤋
Bamma say he never know coconut trees grow so tall. Bamma say he seen redwood up close. Bamma say 1000 feet tall. Bamma say imagine a coconut hitting you on the head from up there. Bamma say you no have to worry about opening it. Bamma say it just open on its own. Bamma always wonder where coconuts come from. Bamma say the coconut tree. Bamma say you learn something new everyday. Bamma say so.
2006-12-19 18:27:20 · answer #9 · answered by Anonymous · 4⤊ 1⤋
It rises through a process known as osmosis. Thats also how the roots absorb water.
2006-12-19 18:23:47 · answer #10 · answered by matrix_testing_ans 2 · 0⤊ 3⤋