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Energy

• Energy is measured in joules (j). There are many forms of energy. Stored energy is called potential energy. Movement energy is called kinetic energy.
• To get a job done energy must be transferred from one place to another.
• The total amount of energy in the universe stays the same, it is conserved.
• §In energy transfers  the energy spreads out and becomes less useful.
• Coal oil and natural gas are fossil fuels. These are non-renewable sources of energy.
• Energy can be obtained from the Sun, plants, wind, waves and water in dams. These are renewable energy sources.
• Atoms vibrate more at higher temperature. The thermal energy (heat) is the total thermal energy of all the vibrating atoms in an object.
• Energy always travels from hot things to cold things. It can do this by convection, conduction or radiation.
• Energy is conducted through an object because the atoms vibrate and bump into each other.
• All metals are good conductors. Air is  a good insulator.
• Hot air rises, in a convection current.
• Energy can be absorbed from the Sun. Hot things radiate energy.
• Black objects absorb more energy (and so get hotter) than shiny objects.

In this section we look at energy sources, types and changes. We have already covered this is Year 7 but now learn a little more and how to draw detailed ETD (Energy Transfer Diagrams).

We looked at how the same amount of energy would heat different volumes of water up to different temperatures. The less the volume of water : the higher the temperature.

Types of Energy

Potential energy including gravitational and strain, chemical, kinetic (movement), light, sound, nuclear, electrical.

Energy can never be destroyed but can change from one type to another. We look at this in detail as part of this section. When we look at energy changes we need to think about how much is changed to useful energy and that some energy is wasted in things like friction, heat and light.

We get our energy from the food we eat. We then convert it into heat energy to heat up your body and kinetic energy when you move and even sound energy when you shout too. Energy is measured in joules. 1 kilojoule = 1000 joules. When we are more active we use more energy. Running about really fast means you need more food to stay the same weight. When you are growing you need energy for that too.

Energy Sources

Where do we get the energy we use at home from? Where does the energy used in factories and shops come from? Well they come from different places but originally all this energy comes from the sun. The main sources of energy we use comes from fossil fuels. These are fuels formed over millions of years deep underground. They are oil, coal and gas. These fuels form when dead animals and /or plants either fall to the ground (coal) or to bottom of sea (oil) and are covered in layers of silt (soil) which then press them together. Heat and pressure convert them into fossil fuels. We dig them up and burn them to release energy. One day (sooner than you think) these energy sources will run out! They will! Before you die for some of them! Isn't that scary?

When you turn on your stereo or TV electricity races through the cable and you hear your music or see 2 stupid dogs on the cartoon network - of whatever! Where does that electricity come from? The simple answer for us in Dubai is Jebel Ali power station. Gas is burnt and the heat produces used to heat water into steam. This steam drives (pushes) a turbine round and electricity is generated.  The electricity is carried in cables on pylons and travels to sub stations and then passes along underground cables to your villa or apartment block. 

Electricity is actually a flow of little particles called electrons. The way they flow is a bit like water. Imagine turning a tap on and water rushes out from the pipe, well, electrons rush along a wire when a switch is turned on.

Alternative Energies

The world is looking at alternative (different) sources of energy because we need lots of electricity to survive with the way that we live and fossil fuels are running out!.

Alternatives need to be pollution free (or only pollute a little). Some examples are:-

• solar panels
• solar cells
• wind
• wave
• hydroelectric
• geothermal
• wood
• biomass
• nuclear fission
• nuclear fission
• energy efficiency!!!!!

We also look at the movement of heat energy.

Sites to help you in this section:-

Click on these pictures for super sites!!!!!

Information on world energy use is available on the Internet, for example, you can research how fossil fuels are used and made over time at this site http://www.energy.ca.gov/education/story/story-html/chapter05.html.

You can research energy sources, and all you might ever want to know about energy at http://www.energy.ca.gov/education/index.html. This site also shows you renewable energy, alternative fuel vehicles and much more. Use the Internet to find how fossil fuels were formed, extracted, and used today. 

http://learn.co.uk/default.asp?WCI=Unit&WCU=3069

What you should be able to do.

• Draw energy transfer diagrams.
• Complete an energy flow-chart for a power station.
• Write down food-energy chains in the correct order.
• Understand charts and graphs showing sources of energy.
• Plan an investigation to see what happens when different amounts of water receive the same amount of energy.
• Do an experiment to conduct energy through 3 different rods.
• Plan an investigation to find out which material is the best insulator.
• Do an experiment to look at convection currents in water.
• Understand the colour-code on a thermogram.
• Plan an investigation to see whether black or shiny objects get hotter in sunshine.