Trees evaporate 900kg of water a day water is raised from roots to the leaves if the average rise of water to be 9m from the ground then how much energy must be supplied per day to raise the water?

That sounds to me like an awful lot of water ... almost a ton, and more than 200

gallons. It must be referring to the aggregate water raised by some substantial

number of trees.

But no matter; the question is still sound.

Energy to lift mass = (Mass) x (Gravity) x (Height) = (900) x (9.8) x (9) = 79,380 joules.

(That's the amount of electrical energy used to operate a 100-watt light bulb for about 131/4 minutes.)

It's also important to note that the process described in the question leaves a

large part of the job incomplete. Raising the water from the roots to the leaves

really doesn't get you anywhere ... If it stopped there, then either the water

would have to drip down out of the leaves in a steady rain, or else the leaves

would have to blow up like little green balloons to hold all that water. Most of

the water that rises from the roots evaporates as soon as it arrives at the

leaves, and that process requires a lot more energy than simply lifting it 9 meters

from the ground.

The latent heat of vaporization for water is listed as 2,257 KJ/Kg. In terms of

lifting water, that's astonishing. It says that the energy it takes to evaporate

some water is enough to lift it 230 kilometers!