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Energy Systems
CARS
What is energy? Energy is very important to us – we use it
every day and we need it constantly.
Energy is defined as ‘the ability to do work’.
The more energy something has, the more work it can do.
e.g. gale-force 100 km/h winds have more energy than a 10 km/h breeze.
The more mass something has, the more energy it has therefore the more work they can do.
Measuring energy To discover how much energy something has,
we need to be able to measure it.
In the same way we measure how heavy something is in grams, we use joules (J) to measure how much energy something has.
We use 1 joule of energy to measure to lift a 100 gram mass one metre.
Measuring energy Because a joule is only a very small amount of
energy, we use other names to measure things with more energy, such as kilojoules (kJ) and megajoules (MJ)
1 kilojoule = 1000 joules 1 megajoule = 1 000 000 joules
We use these terms to measure the energy content of many things, can you think of one?
How much energy is in a drink?
A can of Red Bull, for example, has 480kJ of energy!
Different types of energy
There are many different types of energy around us.
Heat energy is released when things ignite.
A barbeque has a lot of heatenergy and is useful when wewant to cook something quickly.
Different types of energy
Kinetic energy is the energy possessed by objects in motion.
The amount of kinetic energyan object has depends on itsspeed.
The faster an object moves, the more kinetic energy it has.
Kinetic energy also depends on the mass of a moving object.
The larger the mass, the greater the Kinetic Energy
e.g. A bicycle and a motor bike travelling at
same speed the bus has more kinetic energy because it has a greater mass.
Different types of energy
When energy is stored it is said to be potential energy, because it has the potential to do work.
Things which are high up have gravitational potentialenergy, whereas a spring has elasticpotential energy.
Energy stored in chemicals ischemical potential energy.
Different types of energy
Sound is a form of energy caused by vibrating objects.
It travels as sound waves, and the vibrations are received by your ear drums as the sounds we hear.
The louder the sound, the more energyit has, and the more it vibrates your ears
Different types of energy
Light is a form of energy.
Burning chemicals, very hot objects and stars all release light energy.
Light energy also travels in waves.
Light energy from the sun is called solarenergy and is used by plants to make food.
Different types of energy
Electricity is electrical energy and is widely used because it travels quickly and easily, and can be changed into other forms of energy by electrical devices.
Electrical energy can also be storedin batteries and is widely known aselectrical potential energy.
Different types of energy
Energy stored inside atoms is called nuclear energy.
It can be released from some atoms, such as uranium atoms, in nuclear power stations.
The nuclear energy can be efficientlyturned into electrical energy we use.
Energy changes
Energy can be changed from one form to another by simple processes.
This is called energy transfer.
Energy transfer causes energy to move from one object to another, such as kicking a soccer ball, where the kinetic energy of the player’s leg is transferred to the ball.
Or …….. In golf. A ball at rest is made to move by a
moving golf club.
Some of the kinetic energy of the club is transferred to the ball
Energy transformation Energy can also be converted/transformed
from one object to another very easily.
If you are feeling cold and you rub your hands together they will become warmer because you are using kinetic energy to rub your hands together, which is then converted into heat energy.
Therefore Kinetic energy Heat energy
Energy transformation
Sometimes more than one form of energy is produced when an energy change occurs.
When a candle is lit the chemical potential energy is converted into light energy, but some of the stored energy becomes heat energy.
Chemical potential energy Light energy + Heat energy
Electrical energy is very useful because it can be easily converted into other forms of energy
Four different converters are shown
Energy ConvertersDevice Energy in Energy out
Toaster
Computer
Hi-Fi
Hair drier
Kettle
Drill
Lava lamp
Electrical
Electrical
Electrical
Electrical
Electrical
Electrical
Electrical
Heat + Light
Sound + Light + Heat
Kinetic + Heat + Sound + Light
Heat + Light + Sound
Kinetic + Sound + Heat
Light + Kinetic + Heat
Light + Sound + Kinetic + Heat
Notice that for each energy change, the most useful energy type is written first, and the energy that is wasted is written
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