Energy

What is energy???• The Earth and the planets are moving around the Sun• Energy is necessary for all these changes and movements• We get this energy from the food and drink that we consume• Cars get energy from petrol and diesel

Where does energy come from???• The Sun is our main source of energy• it sends out energy in the form of solar radiation• The Sun gives the Earth the heat and light that living organisms need• Other sources of energy on Earth: - coal- oil- natural gas- uranium- wind- water

Forms of energy

• Kinetic energy – is energy in motion (moving wind, moving water)• Potential energy – is stored energy (can be stored in water in a lake,

in coal, in uranium or in wood)

Energy can change from one form to another

Other forms of energy• Chemical energy – stored in food, fuel or batteries• Thermal energy – in the form of heat• Light energy – in the form of light• Sound energy – released by vibrating objects• Electrical energy – gives power to homes and industries• Nuclear energy – stored in atoms • Gravitational energy – stored in objects that are high up

Renewable and Non-renewable energy sources

• Renewable energy sources - Are unlimited because they are being replaced constantly- It is also known as green or clean energy

• Non-renewable energy sources - Energy sources that cannot be replenished (made again) in a short period of time- They will eventually run out

• Renewable energy- Geothermal energy- Biomass- Hydropower- Solar energy- Wind energy

• Non-renewable energy- Coal- Oil (petroleum)- Natural gas- Uranium

Disadvantages of non-renewable energy sources•Pollution

•Global warming

• Acid rain

Pollution• During the process of burning

fuel (combustion) harmful substances (carbon dioxide and other gases) are produced

• These harmful waste products affect our health and the environment

The ozone layer absorbs most of the harmful ultraviolet rays coming from the Sun. Gases used in sprays, fridges and fire extinguishers damage the ozone layer. It has got thinner.

Global warming

• Is caused by high levels of carbon dioxide in the Earth’s atmosphere

• It means that the temperature in Earth increases

• The polar ice caps melt, the sea level rises and ecosystems change

Acid rain

• Is the result of the harmful gases (produced in the combustion of fossil fuels) which react with water in the atmosphere

• Acid rain makes water in streams, rivers and lakes toxic

Taking care of our planet• The Three R’s:

- Recycle (glass, paper, cardboard, plastic)- Reuse (bottles and plastic bags)- Reduce (the waste that we produce)

Ten small steps • Separate rubbish into different bins• Turn off the lights when you leave the room• Turn off other electric things (TVs, computers) when you’re not using

them• Have a shower instead of a bath• Turn off the tap while you’re brushing your teeth• Use special light bulbs that save energy• Reuse plastic bags when you go shopping• Use rechargeable batteries• Use public transport, cycle or walk• Use recycled paper