1. Why is water carried against the force of gravity up the stem of a plant?
2. Why is
less dense when frozen enabling aquatic life to remain alive?
3. Why is water a good
lubricant?
1. Water rises up the capillaries in plants mostly
due to osmotic pressure (see Biology) although there is a little capillary action. Capillary
action is the way in which water can rise up a narrow capillary tube and is due to the
attractive forces between water molecules and glass molecules.
2. The fact that ice
has a lower density than water means that it will form on the surface of water and so aquatic
life can continue in the water beneath the ice. When the ice has formed it also acts as an
insulating layer and so the water below it is "more difficult" to freeze.
3. Water is a
good lubricant because it is a liquid. However the fact that iron rusts when in contact with air
and water makes water not very practicable as a lubricant for iron based materials such as
steel.