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Energy

What you should know.

• Energy is needed to get jobs done or to make things work.
• To get a job done, energy must be transferred from one place to another.
• The unit of energy is the joule (J).
• To lift an apple from the floor onto a table needs about 1 joule.
• Energy can be stored. Stored energy is called potential energy for example, chemical energy, strain energy and gravitational.
• Movement energy is called kinetic energy.
• The energy law: the amount of energy before a transfer is always equal to the amount of energy after the transfer, but not all of the energy is useful.
• You need energy for doing things. Animals get their energy from the potential energy stored in food.
• Energy stored in food is often measured in kilojoules (kJ).
• One Kilojoule = 1,000joules.
• Manual workers need more energy than office workers. Males usually need more energy than females.
• Fuel store energy. We burn them to get the energy.
• Different fuels are used for different purposes.
• Fossil fuels are non-renewable sources of energy (they get used up).
• We can get energy from the sun, wind and waves. These are renewable sources of energy.

In this section we look at energy sources, types and changes. We name these simply and also have a super homework and practical to look at the changes when a water (masafi) bottle is propelled as far as we can make it. Students need to design a method of propelling the bottle as far as they can beyond a line. After the line they are not allowed to touch the bottle. They are allowed to use 2 pencils, cellotape, glue, paper, card and elastic bands only.

Lets look at some of the designs we have had in 2001 .......

We tested the designs on the school playground. Some went further than expected. It was an excellent practical. Check out some pics of the action!

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!!!!!

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.
• Look at an experiment and list the energy transfers.
• Plan an investigation of a clockwork toy to see how the distance traveled depends on how much it is wound up.
• Look at food labels and understand the energy information on them.
• Explain what happens if the food that you eat contains too much or too little energy.
• Keep a record of all the food that you eat in 24 hours.
• Add up energy intake from the food you have eaten during 24 hours.
• Understand a bar-chart showing the energy intake of people in different countries.
• Understand pie-charts showing the energy sources for the UK and the world.
• Plan an investigation to find the amount of energy given out by different fuels.