Water
Transcript
00:00Water Water is the primary need of mankind.
00:08We cannot live without water.
00:12Plants and animals also need water.
00:15Now let us study the importance of water in this chapter.
00:22Water Water covers about three-fourth of the earth's
00:26surface.
00:27Oceans, rivers and lakes are the main sources of water.
00:37Forms of Water Water exists in three forms, namely ice, water
00:44and water vapour.
00:47On heating water changes into water vapour.
00:55And on cooling it changes into ice.
01:00Water and water vapour do not have a fixed shape.
01:05Ice has a fixed shape.
01:08Sources of Water We get water from different sources, like
01:13rain, rivers and lakes, streams, ponds, hand pumps, taps, wells and tanks.
01:28Purposes of Water Water is useful to us in many ways.
01:33We use water for many purposes, like drinking, cooking, bathing, to wash away dirt.
01:42And water is needed for the plants to grow healthy and look fresh.
01:50Water Cycle The water vapour goes up into the air and
01:55cools to form tiny water droplets.
01:59These tiny droplets join to form clouds.
02:04When the water drops become heavy, they fall down as rain.
02:09And again it goes up as water vapour.
02:15Water Supply at our Homes In cities we get water from the public water
02:21supply system through pipes.
02:24The water is drawn from rivers and lakes and purified in water houses.
02:30The purified water is collected in huge tanks and from these tanks water is supplied to
02:37our homes with the help of pipes.
02:41In India many villages do not have taps.
02:45So the people depend on wells, tube wells and hand pumps for water.
02:53Storing Water At home the water from the taps is collected
02:59in buckets, jugs and bottles.
03:02The water must be collected in a clean vessel and it should be covered.
03:08If we still find that the water is not clean, we can boil it.
03:16Wasting and Polluting Water Do we really waste water?
03:21Yes!
03:22We see that people waste a lot of water while brushing, washing their face or while washing
03:29vegetables.
03:32Wastage of water should be avoided at all costs.
03:36Our rivers are also polluted by waste from factories, bathing animals, washing clothes,
03:43throwing waste from homes etc.
03:46So we should be careful about water and we should never waste and pollute water.
03:54Summary Water covers three-fourth of the earth's surface.
04:01Water is found in three forms – ice, water and water vapour.
04:08Water can be changed from one form to another.
04:12The water cycle goes on in nature.
04:16The water must be collected in a clean vessel and it should be covered.
04:24polluted by waste from factories, bathing animals, washing clothes etc.