about water and its different states
The free surface of water
is a free surface?
A liquid is in contact with its receptacle but also with air. The
liquid surface in contact with air is also called " free surface ".
Diagram: free surface of water:
stationary vessel, the free surface of water is always flat and
horizontal whatever the inclination of the vessel.
Diagram: free surface of water
in an inclined beaker
of the liquids
Diagram: water in a beaker, an
erlenmeyer and a measuring cylinder
If liquid water is transferred into graduated containers of different
shapes, it can be observed that water takes the same shape as its
container but keeps the same volume.
water has its own volume but no own shape.
Properties of solids
an ice cube is poured from one container to another it keeps its shape
and its volume
has its own volume and its own shape.
Properties of gases
gas enclosed in a container occupies all available space: it thus has
no own shape.
If some air
is enclosed in a plugged syringe its piston can be moved to reduce or
to increase the volume of the air: air therefore has no own volume.
To sum up:
The sand (like other substances composed of powder or grains) has
properties that are close to those of liquids.
Each grain has a own shape and a own volume but the sand takes the
shape its receptacle: it therefore has no own form (like a liquid).
However unlike liquids, its free surface isn't necessarily flat and
Learn more about water and its
Basic properties of fluids and definition:
Properties of gases:
Properties of liquids, solids and gases explained for grade 4: