Science Book in 6th Standard - Part 1

Just now I and my wife sneha completed reading Part 1 of Science textbook used in 6th Standard school.

Yes we went back reading old books now a days to recap once again our old school books.

It took 2 weeks to complete the part I.

Sometime later in next month i will update the 2nd part.

Let me know if any one needs any information.

Few important quotations from this book.

1) Is the Earth at rest? No, it is moving continuously in space around the Sun. But we do not feel this motion. This is, because everything around us is moving along with the Earth.

2) Solar System consists of 9 planets

a) Pluto
b) Neptune
c) Uranus
d) Saturn
e) Jupiter
f) Mars
g) Earth
h) Venus
i) Mercury

3) The Sun and all the bodies revolving around the Sun is called Solar system. Our solar system is made up of nine planets, moons,
asteroids and comets. All are revolving around the Sun. The planets are Mercury, Venus, Earth,Mars , Jupitor, Saturn,
Uranus, Neptune and Pluto. Sun alone emits light. All other bodies including moon reflect that light.

4) A smaller body revolves around a planet is called moon. Moons are available for all planets except for Mercury and Venus. Our Earth has one moon.

5) This article says why mercury and venus donot have moon.

6) This article made me recollect what is a light year. What a shame to me to forget :-)

7) Mercury is the smallest planet and the nearest planet to the Sun. The biggest planets are Jupitor and Saturn.The farthest planet is Pluto.

8) Comets are small Solar System bodies that orbit the Sun and, when close enough to the Sun, exhibit a visible coma (atmosphere) or a tail — both primarily from the effects of solar radiation upon the comet's nucleus. Comet nuclei are themselves loose collections of ice, dust and small rocky particles, measuring a few kilometres or tens of kilometres across.

9) Asteroids, also called minor planets or planetoids, are Solar System bodies smaller than planets but larger than meteoroids (which are commonly defined as being 10 meters across or less),[1] and that are not comets. The distinction between asteroids and comets is made on visual appearance when discovered: comets must show a perceptible coma (a fuzzy "atmosphere"), while asteroids do not.

10) When you look up at the stars,does it sometimes seem to you that you can trace out squars, letters and other familiar figures? The group of stars forming a particular shape is called constellation . Orion,Taurus and Ursa Major are some of the constellations.

11) The light from the Sun lights up only one side of the Earth and all the places on that side are having daytime.The sunlight will not reach the other side of the Earth, there it is night-time. Night turns into day and day into night because the Earth is rotating about an axis passing through the north and south geographical poles. It takes 24 hours to complete one rotation. On the night side of the
Earth, the light comes only from the luminous stars and the moon.

12) Moon is the natural satellite of the Earth. Moon is not a luminous body; it gives out no light of its own.We can see it, because it reflects light from the sun. It rotates about its own axis and also revolves around the Earth. For both motions, the time is same, 29.5 days. We can see only one side of the moon. The other side cannot be seen.

13) During the motion of the moon,if both the Sun and the moon are in the opposite part of the sky, we can see the moon. It is because, the reflected light from the moon comes to us. Now that moon is called Full moon.

14) Mountains, deserts, oceans,rivers and land are available on the surface of the Earth. What about its inside? Is it solid like a cricket ball or hollow like a foot ball?

The interior of the Earth can be broadly divided into three different layers. These layers are known as crust, mantle and core

15) Crust:
The crust is the Earth’s solid outer layer. It is upto 30 Kilometres thick under the mountains, but only 6 kilometres thick under the oceans. The crust contains materials like water, rocks and soil. Limestone,common salt, coal, petroleum, metals like iron, copper, aluminium and gold are the different types of minerals found in the Earth’s crust.

16) Mantle:

The layer in between the crust and outer core is called the mantle.Its thickness is nearly 2900 Kilometres. The mantle is made up
of hot rocks. The temperature and pressure is more than in the crust. The mantle layer is in semi-molten state.

17) Core is made up of 2 parts
a) Outer Core and Inner Core

Outer Core:

It lies in between the mantle and the inner core. It is 2240 kilometres thick. This outer core is made mainly of metals. It is under enormous pressure and so hot. The metals are in molten state. Four-fifth of the outer core may be iron and nickel. The rest one-fifth is probably silicon.

The inner core is a solid ball. It is about 2440 kilometres thick. Like the outer core, it is also made up of iron and nickel. The temperature is about 3700oC.

18) The air that surrounds the Earth is called atmosphere. It extends up for hundreds of kilometres. The atmosphere consists of gases like nitrogen, oxygen, argon, neon, helium,krypton, xenon, water vapour, carbon dioxide and sulphur dioxide. Human beings and animals need oxygen.

Plants need carbon dioxide for preparing their food. About 78 percent of air is nitrogen about 21 percent is oxygen and the remaining one percent consists other gases .

99% of the air is found upto a height of about 30 kilometres. This layer of atmosphere is known as troposphere. This is the layer nearest
to the earth.

19) A small experiment which shows the presence of oxygen in air.

The oxygen in the atmosphere helps in burning. The nitrogen in the air keeps the burning under control.The atmosphere allows only a part of light and heat from the Sun to reach the surface of the Earth. The suitable temperature of the Earth is only due to the presence of atmosphere. This helps in the existence of life on Earth.Water vapour in the air makes surrounding as cool.

20) Fix a small size candle at the centre of a trough. Fill it with water.Candle should not be submerged in water. Now, light the candle. Then, place a glass tumbler upside down such that it must cover the lighted candle. What happens?

The candle needs oxygen to burn. The air available in the tumbler has oxygen. With this oxygen the candle burns. After sometime, the
candle blows out. This is because, the entire oxygen has been used up. No more oxygen is available. This shows the presence of oxygen in air.

20) Ocean currents are like rivers of water flowing through the ocean. They are warmer or colder than water through which they pass.

21) Many useful materials are in the ocean. Most important among them are the common salt and iodine.

22) Conversion of water into vapour is called evaporation.Heated by the Sun, water on the surface of lakes, rivers and oceans evaporates and become water vapour in the atmosphere. It joins with the water vapour released from the leaves of plants and forms clouds. When the
clouds are lifted by upward motion of air, they cool. This can make the water vapour to condense into tiny water droplets. Often they freeze into tiny ice crystals and start to fall. They are too heavy for the air to keep them up. They reach ground as snow or melted as rain after melting.

23) The water you drink today may have been drunk by someone thousands of years ago!

24) Water, atmosphere with oxygen and carbon dioxide, suitable temperature and food are available only in our Earth. Hence, life exists
only on the Earth. In the other planets the above said things are not available. So life is not possible in other planets

25) The space occupied by an object is called volume.

26) Volume of cuboid = length × breadth × height.

27) Mass is the quantity of matter inside the body. Weight is the pull of gravity on the object. Weight of a given object is
variable from place to place and planet to planet.

28) Sundial

An early device for measuring time was the sundial. A simple sundial is made of a horizontal circular board with a triangular plate
of metal fixed vertically on it. The plate is fixed along North-South direction. The shadow of the plate falls on the board. The edge of the shadow falls at different angles at different times of the day. The position of the shadow was used to note the time of the day. It cannot be used after sunset

29) 'Anything that has mass and occupies space is called matter'.

30) Prick an inflated balloon with a pin. The air inside the balloon comes out with a force and noise . What is the reason?

Answer:

The particles in a gas are far apart from each other and are held together by very weak forces of attraction. So they move very easily.
Gases have the property of fludity. i.e. moving spontaneously from a region of high pressure to a region of low pressure.

31) We enjoy when it rains. How do we get the rain from the sky? The water vapour in the cloud gets cooled and forms tiny particles of water. These water particles unite and form water drops which fall as rain

The change of state from vapour into liquid by cooling is called condensation.

32) Take a vessel. Fill it with hot water. Put the two spoons in it. One is made of metal like aluminium or stainless steel and the other is made of wood or plastic. After some time, touch the two spoons by your left and right hand. Which one is hotter? The metal spoon is hotter than wooden spoon. Why? Metals quickly conduct heat. So, metals are good conductors of heat. In metals, heat flows from one end to another quickly.

33) In the materials like wood and plastic, heat flows from one end to another very slowly. Wood, paper, cloth and plastic are bad conductors of heat.

34) The metal mercury, which is a liquid, is a good conductor of heat.So, we are using the mercury in thermometers. Gases are poor
conductors of heat.

35) Have you seen the electric cable? Take a piece of unused cable or wire. Cut and open the outer coloured layer (insulating material). Inside, you find a number of thin metal wires (copper aluminium). These metal wires carry the current. Metals are good conductors of electricity.

36) The outer coloured layer will not carry the current. This insulating material, paper, dry cloth and rubber are bad conductors of electricity and are called insulators.

37) Pure water is a bad conductor of electricity. However, water (what we are using) containing dissolved salts conducts electricity. It is not advisable to touch the water in which electric current flows. It is advisible to always wear rubber chappals (insulators) and
to keep the hands dry while operating electrical appliances. Thus, we conclude that matter can be classified as conductors of electricity and insulators.

38) That is why electric wires are made up of metals. Metals are good conductors of electricity.

39) We cannot see through a paper, a metal sheet, a wall and wood. All these are opaque materials. Light cannot pass through them.

40) We can see through a glass. So glass is a transparent material. We can see the fish in clean water. So clean water is also a transparent material.We are surrounded by air, and objects are always seen. So air is also transparent material. We may conclude that the materials which allow the light to pass through them are called as transparent and those which do not allow the light are called as opaque

41) Sedimentation : The mixture containing solid and liquid components is allowed to stand for sometime. The heavier particles settle at the bottom of the liquid. The process of settling down of insoluble particles in a suspension is called sedimentation.

42) Decantation : The process of transferring the clear liquid standing above the sediment carefully into another container using a glass rod is called decantation.

43) The changes which occur again and again at regular intervals of time are called Periodic changes

44) The shortest distance between the two positions is called displacement. The distance in a particular direction is called displacement.

45) The speed in a particular direction is called velocity. That is the velocity is defined as the rate of change of displacement.

46) We have seen that forces change the motion of a body. If we roll a ball on the cement floor and another ball on the polished floor, in the second case the ball moves fast and long distance than in the first case. It happens because of frictional forces.Friction arises when surfaces of two objects are in contact.

47) Since the mass of the moon is much smaller than that of the Earth,the gravitational force on objects is less on the moon. This means that the weight of a given body will be less on the moon than it is on the Earth. The weight of anything on the moon is about one sixth of its weight on the Earth.

48) The ratio of the force and the area on which it acts is known as pressure. In other words pressure is equal to force per unit area.

49) that increase in pressure at a point within the liquid at rest is communicated equally to every other point within it. This principle is known as Pascal’s law.

50) Thus there is a relation between work done, force applied and the distance moved.

51) Simple machines are used to increase the effect of force or change the direction of the applied force or both. There are six kinds of simple machines. They are (i) the lever, (ii) the inclined plane, (iii) the wedge,(iv) the screw, (v) the wheel and axle and (vi) the pulley.