SCIENCE Section 2: Energy Summary Section2- 1 -

Name class .

Why we need energy.

•to keep your body working you need energy from food

•for heating homes, schools and offices we need fuel

•to drive machines in industry we need fuel or electrical power

•we need energyto power cars, buses, aeroplanes, ships and other forms of transport.

Types of Energy

You need to learn and recognisethe types or forms of energy listed below.

Heat,light, sound,kinetic(movement), work done, chemical, nuclear (atomic), potential (stored), mechanical.

Useful Energy in Action

Energy does lots of important jobs around the house eg

  • Fires, kettles and cookers supplyuseful heat energy.
  • Electrical energy is used up when it is put in to makeI-pods, washing machines and mobile phones work.
  • Food mixers, fans, electric drills and vacuum cleaners give out useful kinetic energy.
  • A cake has chemical energy as do the candles on the top.

Measuring Energy

The unit for measuring energy is the joule (J).

One kilo joule is 1000 joules

1kJ = 1000J.

You used a Joule meter (energy meter) to measure the energy used by different devices. Devices that produce heat tend to use the most energy eg tumble driers.

Energy Sources

The energy to make things happen comes from energy sources..

Energy sources are not types of energy .Sources provide us with a supply of types or forms of energy.

The main energy sources are

  • Fossil fuels e.g. coal and oil in power stations
  • Nuclear power stations
  • Hydroelectric power stations
  • Solar energy from the sun is used in solar panels or solar cells or infra red arrays or by growing plants
  • Bio mass e.g fast growing Willow trees, certain sea weeds
  • Wind e.g. in aero generators
  • Wave power
  • Tidal power to turn water turbines as the tide goes in and out

Non renewable sources of energy

A non renewable source of energy will not last forever.

Fossil fuels are non renewable , they will run out because we use them faster than they are created.

Fossil fuels affect global warming because they give out a lot of carbon dioxide gas when burned.

Renewablesources of energy No matter how often a renewable source is used, the source will not run outExamples of renewable sources are solar energy,wind,biomass,waves,tidal,hydroelectric.

Energy change systems.

Energy can be changed from one form to another,

In a light bulb, electrical energy is converted into useful light energy and somewasted heat energy.

Energy change situation or system / Type of energy
A sledge at the top of a hill / Haspotential (stored) energy
Uranium is a fuel usedin nuclear power stations and
for making nuclear weapons / Has atomic energy or nuclear energy stored in the fuel
The water held back behind a dam is high up ,compared to the river below the dam. / Has potential energy
A wound up spring in a wind up torch or watch / Has potential energy

In a television electrical energy is converted into light and sound energyand as unwanted heat energy.

Electrical light and sound

The arrow points from the first type of energy and points to the new transformed type of energy.

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Cold cake has chemical energy stored inside it so it canstill provide us with heat energy when we eat it.

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Eating the cake Chemicalheat in the body

Burning the candleChemicalheat and light in the flame

Energy and cars

Good design features for a car would be

Feature / Effect / Impact
Streamlined / Cuts fuel usage good km/l / Cuts global warming, cheaper to run
Modern efficient engine / Cuts fuel usage high km/l / Cuts global warming, cheaper to run
Uses non fossil fuels e.g..air compression or electric engine / No direct use of fossil fuels / Less pollution cuts global warming
Recyclable parts / Saves money and cuts energy usage / Conserves energy and resources

To save energy when driving we need to usegentle acceleration and have no harsh braking.

The sun

Our most important energy source is the Sun Energy that comes from the sunis called Solar Energy. The main forms of solar energy are heat and light.

The sun produces energy because a nuclear reaction called fusion converts mass into solar energy.

Ozone layer

  • The sun also gives off invisible radiation e.g.ultraviolet, radio waves and microwaves.
  • Ultraviolet (UV)is dangerous and can cause cancer or blindness in humans. UV also causes us to have a sun tan.
  • We are protected from UV by the Ozone layer in the upper atmosphere.
  • The Government has banned people under 16 from using sun tan beds which give off UV light because the beds are more likely to cause skin cancer in young people.

Global warming

  • In the Earths atmosphere the heat radiation from the sun is absorbed by green house gases like carbon di-oxide and methane so less heat escapes from the earth.The extra heat causes Global warming.
  • Global warmingis expected to have major effects on climate and sea levels in the near future.
  • Car exhaust gases,gases formedburning fossil fuels and digestive gases from livestock are all green house gases.

Thermal Power stations

These provide us with electrical energy by using fossil fuels or nuclear fuel, or the suns reflected rays,as a source of energy to heat water.

How we get electricity from a thermal power station

Thermal stations include;

Convection towers, reflecting mirror stations, power towers,solar panels, peat and bio-mass, geothermal,Infra red antennae, solar panels and in the future fusion power reactors.

Non thermal power stations (Alternative sources)

Potential or kinetic energy turns turbines which then spin generators to produce electricity.

e.g. Hydroelectric power station. Potential energy in the water in the dam gives water enough kinetic energy to turn turbines…etc etc..

Non thermal power stations include;

Examples are aero generators, tidal flow power stations, wave power ‘Ducks’ , photovoltaic arrays (solar panels)..

Sources and their main types of energy

SourceTypes of energy

oilThis fossil fuel is a source of chemical energy

coalThis fossil fuel is a source of chemical energy

gasThis fossil fuel is a source of chemical energywaves This is a source of kinetic and potential energy wind This is a source of kinetic energy

geothermalThis is a source of heat energy

Sources and their main types of energy

SourceTypes of energy

water in damsThis is a source of kinetic and potential energy

foodThis is a source of chemical energy

biomassThis is a source of chemical energy

tidal waterThis is a source of kinetic and potential energy

photovoltaic panelsThese are a source of electrical energy

atomicThis is a source of heat energy.

batteriesThese are a source of electrical energy

Formation of Fossil fuels.

Coal and gas

  • Many millions of years ago the Earth was covered in swamps into which, plants growing nearby died and fell into the swamps where they slowly began to rot.
  • Gradually, over the years, this rotting vegetation was covered with mud and sand building up layers of rotting plants and earth.
  • The weight of these layers caused pressure which squeezed these layers together so the pressure and heat underground made them chemically react to harden and form solid seams of what we know as Coal.
  • Coal is removed from the ground near the surface in open caste mines or in deep pits dug through underground layers

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Oil and gas

  • These formed over millions of years when microscopic marine animals died and fell to the bottom of the sea bed where they decayed and were buried under layers of sand and rock.
  • The pressurecompressed these fossilised remains to form oil and gas.
  • We call coal, oil and gas fossil fuels because they have been formed from the fossilised remains of plants, trees and microscopic marine animals.
  • Oil is removed from the ground by drilling wells so the pressure underground forces the gas and oil up the pipes to the oil rig on the surface.

Test Preparation

This takes time even if you have been working well throughout the section.

You should plan to spend one or two hours preparing for the test.

See the main version of this summary on the school science web page for further details.