Energy Systems CARS

e.g. gale-force 100 km/h winds have more energy than a 10 km/h breeze. 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 heat energy and is useful when we want to cook something quickly.

Different types of energy Kinetic energy is the energy possessed by objects in motion. The amount of kinetic energy an object has depends on its speed. 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 potential energy, whereas a spring has elastic potential energy. Energy stored in chemicals is chemical 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 energy it 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 solar energy 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 stored in batteries and is widely known as electrical 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 efficiently turned 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 Converters Heat + Light Sound + Light + Heat Device Energy in Energy out Toaster Computer Hi-Fi Hair drier Kettle Drill Lava lamp Heat + Light Electrical Light + Sound + Kinetic + Heat Sound + Light + Heat Kinetic + Heat + Sound + Light Heat + Light + Sound Kinetic + Sound + Heat Light + Kinetic + Heat Notice that for each energy change, the most useful energy type is written first, and the energy that is wasted is written last.