a many-sided element. Water and Life.
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Water is very simple, but it behaves as no other material and it has got some specialqualities. Because of these qualities water‘s essential for life. Without it, life couldn‘t exist. It couldn’t exist on the Earth and anywhere in the space. Therefore water isconsidered an essentialrequirement of life.
The first living organisms appeared on the Earth about four billion years ago. They lived in water which protected them from the ultra-violet radiation.
The first living organisms left the sea much later, about half a billion years ago. They tookthe water in themselves and stayed dependent on it. Water creates about two thirds of our own bodies.
The sea water is 95% of the totalamount of water in the world.There are some dissolved substances in the sea water and salt is 99% of them. In the tropical sea the content of salt is the highest because a bigger amount of water is vaporized than it gets back.
Atributes of sea water – colour:
- the shade of the water is influenced by the absorbing sun shine and sky coulour, depends on the content of plankton and on depth.
-blue – there is little plankton in the water
-green and red – there are lots of living organisms in the water
-yellow and brown – these are colours ofthe border seas, to which rivers bring minerals
How much freshwater is there in the world?
Decreasing reserves offresh water canresult in great problems in the world. They can appear in Africa in drainage area of the Nile, inAsiaby the Tigris,the Euphrates and the Ganga rivers and Aral lake which used to be the forth largest inland seaand which decreased its area into less than 50% of its original size due to human activities.
Chad lake, which lies on the border of four countries (Nigeria,Cameroon, Niger and Chad) and makes possible life of millionsof people in Africa, looses its water too.Today its area is 1350 km2, but in the year 1963, it was 2500km2.
The reasons of loosing water areglobal warmingand climaticphenomenoncalled El Nińo. They result in the desert increase.
The state or the stadium of water is a form of the substance, which has got characteristic ordering of the particles in the substance and expresses some typical features. The particle is a very small part of the substance which has got some characteristic features (energy, weight, electric charge, spin, chemical reactivity, life span etc.).
We distinquish three states of water: solid state (ICE), liquid state (WATER) and gaseous state(VAPOUR)
Why sharks don´t drown in the water?
Shark is heavier than water and so it should sink to the bottom. To prevent this they haven´t got air bladders as other fish, they have got oil liver. Oil carries the shark, because it is lighter than water. They have so much oil in the liver they would fill up five big buckets.
Why don´t cephalopods give up before fight ?
Cephalopods are very strong. They usually grow up 20 meters and they don´t give up before fight. At first they try to escape in an inky cloud, which they leak as a „smoke screen“ or they turn to the sperm whale and fight back not to be caught. Both animals usually fight untill one of them dies.
Do the seals feel cold?
Seals are warm-blooded mammals. They create and keep fixed body temperature. They can keep it even though they often swim in very cold water. Seals have short hairs or a fur. Under the skin they have got fat. When they swim in warmer water, sometimes they warm themselves up too much and they wave their flippers in the air to cool down.
Does the electric ray give electric shock?
Electric ray has got special muscles in its body which can make electric current of 200 volts. As soon as it attacks fish it kills it with the electric current. The discharge is strong enough to knock out a human when he steps on an electric ray.
Water belongs to the unfailing sources of energy, therefore the production of energy from water is ecological. The energy from water is used in the water power stations. In all power stations except of the sunny power stations the production of energy is based on a generator, which is turbine powered.
Turbine is an equipment, which is constructed for effective transposition of the kinetic energy, which is supplied either by steam or water, into rotation. There are different types of turbines, perhaps the best known and most widespread is Francis turbine, which is used either for horizontal or vertical direction. Francis turbine is an eguipment which consists of a stator and a rotor. After the energy gets on the shaft of the rotor it begins spinning and the electric current is induced.
The antic sailboats were built according to phoenician patterns, short,wide with tall sides, a sparin the middle of the deck,operatedwith one or twowide oars.In 3rd century Vikings started to organize voyages and robberies. Their ships were eqipped with a spar sheet, the hull in the shape of the letter V. Their duration was from 30 to 50 metres, they had 20 pairs ofoars.
On the voyages across the ocean Portuguese sailboats started to be used. They were 15-20 meterslong,lightand fast. They had sheetss,which enabled them to sail up the wind.In 15th century a new type of ship appeared in Spain. It was called galeona.This ship was 40meters long and 12 meters wide with 3 or 4 spars. Later the sailboatswere replaced by steamships, liners and ferriess.
In 1807 Robert Fulton built the first steamship
for transport of people (North River Steamboat
of Clermont). About 50 passengers could go on
its board. In 1812 a steamship Cemet was able
to sail at the speed of 7 knots. In 1820 it
wrecked. In 1829 a Czech inventor Josef Ressel
patented his boat wood-screw.
Break occurred in 1845, when J.K.Brunel launched a business steamship called Great Britain for 360 passsengers. From 1900 to the 1914 the biggest stemships for transport of people were built. Their lonqitude was over 200 metres and they could transport more than 4000 people.
The first sketch and descriptionof submarine was presented by a Venice army engineer Robert Valurioin 1472. The first manufactured submarine was just a toy. In 1620 a Dutch doctor and inventor Cornelius van Drebbel constructed it . It was built from wood and was protected byoily skin.
American David Bushell designed a one-seat submarine Turtle. It consisted of two iron hemispheres.In 1800 Robert Fulton presenteda submarine Nautilus. It was hand-operated and it could sail for 4,5 hours under water.
First sumbarine driven by an electricmotor was bulit in 1884 by a Polish designer Drzewiecki for tsar Alexandr 3. It was equiped by a scope and2 bombs .In 1910 a diesel-elektric motor was constructedand was used in submarines. During World War II submarines were widely used and their equipment (for example a radar) improved .
It is an undersea craftwith its own gear which is used for exploring the extreme depths. It consists of a spherical cabin for observation, a system of floats and balast which help the batyscape to move up and down..
Human activitiescause pollution of water and also destroy life in it. The pollution is caused by: industrial waste, oil spots, motor oil which gets to to drainage etc.FARMINGWorldwide 70% of water is used forirrigation. Chemicals such as pesticides and animal waste decrease the quality of water.In some rivers and lakes the amountof oxygen is so low, that no water life is possible there.
INDUSTRYOur water flows are polluted by industrial production for example of aluminium,steel or plastic.Wood-working industry partakes on decreasing area of the tropical rainforest.HOUSEHOLDSIn the regions wherewater supplies are big enough people oftenwaste water.Average annual consumption of water in an ordinalhousehold is 200 000 litres.In our households, a big amount of chemicals is used –colours, glues,oils and detergents.If they are poured to the waste water they get to the rivers, lakes and seas.
The spring of the Svratka river is in the Žďár’s hills. The river is 152 km long. There are three damson the Svratka river. They are sourcesof drinkable water. The stream-bedof the river is quite narrow. In the valley of the Svratka river some castles, churches andmonasteries were built in the Middle Ages .
The spring of the Svitava river is in Javorník near Svitavy. Theriver is 73 km long. Inthe upper partdown to Letovice there area lot of weirs. The Svitava is a source of drinkablewater.The Svitava has an inflow of of the Punkva river. It runs throughthe Moravian Karst.
Water – a simple word, which is known by every one. It isnecessary for our lives. It refreshes, cures, but it is also a wild element which is very difficult to escape from.
About 8 years agowe faced descructive floods in Moravia and in 2002 water showed us its incredible power again. During holidays, in July 2002, on various places ofour republic thick black clouds with rain stormsbegan to appear.That timesome local claims were caused. But the worstdamages were caused by the wild water element in August 2002.
Some people uselessly riskedtheir lives.
They did not want to help rescuers, they
stayed in theirhouses and some hours later
they had to be saved by helicopters. There
were many cases of people loosing their
houses whichfell down in the flood and a few
houses whichfell down in the flood and a few
people lost even their own lives.
Near Brno we can find Kníničky’s dam named after a flooded village Kníničky. It is situated on the Svratka river about 8 km northwest of the Brno centre. The concrete dam is 34,5 m high and 120 m long. There are about 21 million m3 of water in the reservoir.
The dam is an important recreation centre of Brno city . That is why there are various stands and fast foods as well as sport centres. The lake is
suitable for yachting and windsurfing.
The idea of building a dam appeared in the beginning of 20th century. It should be a protection from the annual floods on the Svratka river, a source of the electrical energy, a source of drinking water and a recreational centre..
We have chosen a name of the friendly water animal as the maskot of our team. But there is one important difference between seals and us: unfortunately there is no sea in the country where we live.