LIGHT
NO one can see anything in a completely darkned room. There has to be light before you can see. You see when light enters your eye. And so you have to know something about light to understand how the eye Works.
WHAT IS LIGHT?
Light is a kind of energy. It’ s a type of radiation. Light energy is given off by a sun, by electric light, bulbs, by candles, and other light sources. Light energy travels from one place to another.
The light travels in atraight lines. (You can see that from the picture of the sun). It’ s often useful to think of the light travelling as light rays. The rays are like tiny beans of light, travelling through the air at 300.000 km each second.
SHADOWS AND REFLEXIONS
Because light tralvels in straigh lines, shadows form.
WHAT IS SHADOW?
Is an area behind on object where no light from a light source reacines.
When the sun shines on an object like a tree, the sun’ s cannot bend round cornrs to reach the area behind it. That’ s why the area behind the tree is dark, and that’ s what makes. The shadows light rays can be bounced off, or reflected off an object you see thid board because rays of light are being reflected from it into your eye. Shiny, surfaces, like a mirrors reflects light best you can see how a mirror reflects the rays.

LIGHT AND SOUND

The light comes from the sun. it is quite high up in the sky because the shadows are long ( vertical plane).
other sources of light are: the lamps, candies, torches, screen,and so on.
natural sources of light:the sun amd the moon.the shape and the size of the shadow depends on the shape of the object that is causing the shadow and its orientation with respectto the source of light.
SOUND: Intense sounds can be heard from a greater distance from the place of origin than weaker sounds. for example: the sound made by a computer can heard when we are working on the computer but not if we are 40 or 50 meters away the pitch is defferent also much more intense sounds are made on a drum than on a guitar.

red car goes black

You will need:- 1 Strong Torch and rubber band.- Green Cellophane- 1 Red object e.g. car, tomato, hat- A very dark room Instructions1. Place the green cellophane over the torch and secure with a rubber band.2. Darken the room and shine the green light on the red object4. What colour do you see? Try different coloured objects and lights. Is the effect always the same?

letter 2070

I think that now we must begin to take care of our planet that we want to stay no more adente without water or better than ever, we will spend what is supposed to happen in 2070 that the losers will be our children. Also paresce me that the president of each country to propose a campaign to ensure the most planeta.Y obviously people need help for us

WHAT IS MATTER?

Every thingthat surrouns us is made up of matter. The air, animals, rocks, plants every thing.We cout define matter as all that occupies a space and can be weighed. Even gases wich are very light, can be weighedif we weigh and inflated balloon we can see that it weighs slightly more than an un. inflated balloon. When we are studing matter we use sam basic quantities such as length, surface, area, volume, mass, density or temperature. So that we are all using the same units in science we use what is called the internationalsystem of units.
DIMENSIONS: Length (L) is the distance betteen two bodies.In (SI) units this is mesured in meters(M) we also use centimeter(CM) or kilometers (KM) we use rulers, measuring tapes and so on when we are measuring length (L).
SURFACE AREA (S): Is the space occupied by two dimensions length (L) and width. In (SI) units we measure surface area in square meters (M2) and other very common unit is square centimeters (CM2).
VOLUME (V): Is total space ocupied by a body. It is often measured in litres even in the (SI) unit in the cubic meter (M3) the volume of liquids or solids can be measured using measuring cylinders in the case of regular geometric chapes we can use mathematical formules for example:the volume of a sphere with radius is Vsphere =4/3 valius of PI R3.

ALTERNATIVE SOURCES OF ENERGY

Solar energy is one the most resourceful sources of energy for the future. One of the reasons for this is that the total energy we recieve each year from the sun is around 35,000 times the total energy used by man. However, about 1/3 of this energy is either absorbed by the outer atmosphere or reflected back into space (a proccess called albedo)1.
Solar energy is presently being used on a smaller scale in furnaces for homes and to heat up swimming pools. On a larger scale use, solar energy could be used to run cars, power plants, and space ships (like the picture you see above) .


Wind Power
Wind power is another alternative energy source that could be used without producing by-products that are harmful to nature. Like solar power, harnessing the wind is highly dependent upon weather and location. The average wind velocity of Earth is around 9 m/sec. And the power that could be produced when a wind mill is facing the wind of 10 mi/hr. is around 50 watts.1


What is GEOTHERMAL ENERGY ???
Geothermal energy is an alternative energy source, although it is not resourceful enough to replace more than a minor amount of the future's energy needs. Geothermal energy is obtained from the internal heat of the planet and can be used to generate steam to run a steam turbine. This in turn generates electricity, which is a very useful form of energy.

Tidal Power
Even the power of the tides can be harnessed to produce electricity.
Similar to the more conventional hydroelectric dams, the tidal process utilizes the natural motion of the tides to fill reservoirs, which are then slowly discharged through electricity-producing turbines. The former USSR produced 300 MW in its Lumkara plant using this method.


Hydroelectricity
Hydroelectricity comes from the damming of rivers and utilizing the potential energy stored in the water. As the water stored behind a dam is released at high pressure, its kinetic energy is transferred onto turbine blades and used to generate electricity. This system has enormous costs up front, but has relatively low maintenance costs and provides power quite cheaply. In the United States approximately 180,000 MW of hydroelectric power potential is available, and about a third of that is currently being harnessed.

ENERGY SOURCES

throughout history people have obtained energy fromm their own muscles, animals, the wind, running water, several types of fuel. wood, coal, oil, petroleum,etc. and electricity of course traditional sources of energy are still being used.
EXAMPLE:
muscular energy in order to carry out certain tasks animals for pulling cards ploughing the land in developing countris; air currents for sailing boats,wind farms; running water for hydroelectric power stations, river boats; fuel for cars, gas or coal boilers; electricity for household electrical appliances, industrial machinary.