Natural Science and Technology Grade 5 Term 3 Energy and Change and Systems and Control. Topic 10: Stored energy in fuels Unit: 1 Fuels...

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1 Natural Science and Technology Grade 5 Term 3 Energy and Change and Systems and Control 1 Contents Topic 10: Stored energy in fuels... 2 Unit: 1 Fuels... 2 Fuels are sources of useful energy... 3 Examples of fuels and what they are used for... 4 Unit 2: Burning fuels... 4 Unit 3: Safety with fire... 6 How to prevent fires... 6 Topic 11: Energy and electricity... 6 Unit1: Cell and batteries... 6 Unit 2: Mains electricity... 8 Mains electricity comes from power stations... 8 Unit 3: Safety with electricity... 8 How to use electricity safely... 8 Topic 12: Energy and movement... 9 Unit 1: Stored energy... 9 Topic 13: Systems for moving things Unit 1: Wheels and axels... 10

2 2 Topic 10: Stored energy in fuels Unit: 1 Fuels Vocabulary fuel - a substance that can be eaten or burned to produce energy stored energy - energy that is stored in something, e.g. food input energy - the energy needed to start a fuel burning output energy - the energy that is produced when fuel burns Fuels are used in many different ways in our day to day lives. Fuels are substances that can be burned to produce heat or energy. Energy is stored in fuel. We call this, stored energy. The energy is slowly released when the fuel is burnt. Food is a fuel that contains energy. It is seen as fuel for the body. Food is broken down with the aid of oxygen and energy is released into the body.

3 Fuels are sources of useful energy The helpful sources of energy that we use on a daily basis include coal, natural gas and paraffin. We use the stored energy in these fuels for many different things. We heat and light our homes using this energy. We are even able to use it to cook and prepare meals. 3 Candle wax is also a fuel. Candles were originally made of beeswax or different plant waxes. Today they are made from paraffin wax. The energy is stored in the wax and released when the candle burns. Light and heat energy is released. Cars use petrol to make the car move. Stored energy in the petrol is released when the car s engine burns this fuel. The car is then able to move.

4 4 Examples of fuels and what they are used for FUEL Petrol Firewood Gas Paraffin Candle wax Coal Food USE To run engines Heating and cooking Heating and cooking Lighting, heating and cooking Lighting Making electricity at power stations and heating Providing energy to keep our bodies moving and growing Fuels need energy to start them burning. A candle needs a burning match to set its wick alight. The match provides what we call input energy. When fuels start to burn, the stored energy inside is released and changed into other forms of energy like heat and light. We call this output Unit 2: Burning fuels Vocabulary extinguish - to put out fire-fighters - people who are trained to put out uncontrolled fires

5 5 The three most important elements for a fire are: 1. Fuel, e.g. wood 2. Heat, e.g. matches (input energy) 3. Oxygen Fuel, heat and oxygen form the fire triangle. If any of these are taken away, the fire will be extinguished. This means the fire will stop burning. A candle will burn if a match (heat source) is brought near the candle wick. The heat from the flame melts the wax and turns a small amount of the candle wax fuel into gas. This gas mixes with the oxygen in the air to make a flame. The heat of the flames melts the top of the candle wax (fuel) and turns it into a liquid form. It will continue burning until there is no wax left. Fire-fighters are people who assist in putting out uncontrolled fires. To stop a fire from burning the fire-fighter has to stop the oxygen supply. Water is usually used to extinguish a fire. The water will cut off the oxygen supply as well cool the fire and remove the heat from it.

6 6 Unit 3: Safety with fire How to prevent fires 1. Do not play with matches, lighters or any flammable liquids. 2. Fuel such as petrol should never be poured onto a burning fire. 3. Candles must always be placed in sturdy candleholders. Never put a burning candle near flammable objects such as curtains or books. 4. Always place fireguards in front of fireplaces. 5. Never dry clothes on or near a heater or cooker. 6. Cooking should always be done under adult supervision. Never leave pots unattended. 7. If you suspect a gas leak from a cylinder, turn off the supply and call a gas supplier. 8. Do not use damaged electrical appliances. 9. Ensure that a fire is extinguished after having a braai or making an open fire. Topic 11: Energy and electricity Unit1: Cell and batteries Vocabulary electrochemical cell changes chemical energy into electricity battery - a source of stored energy that is made of one or more cells switch - controls the electricity in an electric circuit electrical circuit a system that provides a path for the transfer of electricity

7 7 Torches run on batteries. A battery is made up of one or more cells. There is energy in batteries. An electrochemical cell changes the energy in chemicals into electricity. The energy in the battery is transferred to the bulb of the torch. The electricity is changed into light energy and heat energy. The energy flow is controlled by a switch. The bulb will stop working when the stored energy in the batteries is used up. How to dispose of old batteries safely Chemicals that are harmful to the environment can leak out of old batteries. Soil and water is polluted and people s health is affected. Never put batteries in an open fire as they can explode. Some shops and community waste centres collect old batteries. It is taken to be recycled or to special waste disposal sites that store dangerous The parts inside a torch that carry electricity are joined together in a loop that begins and ends at the batteries. The system is called an electrical circuit. The different parts are called components. For electricity to flow through a circuit, all the components must be connected to each other.

8 8 Unit 2: Mains electricity Vocabulary electricity distribution box - the place where electricity is connected to the electrical circuits in a building wall socket - the part of the wall where an electrical appliance can be connected to an electrical circuit The electricity we use in a house is called mains electricity. We use mains electricity to light our homes and run appliances like televisions. We plug appliances into a socket in the wall. Mains electricity comes from power stations Mains electricity is made in power stations. A power station needs a source of energy. Coal is the main source of energy in South African homes. The electricity is transferred from the power stations to substations and then to places where it is needed such as homes, schools, factories etc. through cables called transmission lines.these transmission lines are supported and carried by huge structures called pylons. Unit 3: Safety with electricity How to use electricity safely 1. Never touch the metal terminals of plugs or bare wires. 2. Do not put things such as your fingers or anything made of metal into electric sockets. 3. Do not let bare electrical wires touch each other as they may start a fire. 4. Always keep electrical wires dry. 5. Do not touch electrical wires electrical wires when your hands are wet. 6. Never use electrical appliances when you are bathing. 7. Do not overload a socket by using too many appliances.

9 9 8. Never try to repair electrical cords and plugs with electrical tape. 9. Replace worn, cracked or broken plugs and cables. 10. Do not pull a plug out by the cord or cable. 11. Turn the switch off at the wall socket before removing the plug. 12. Keep electrical cords away from hot things like stoves. 13. Make sure that lights are switched off when you change a light bulb. 14. Never place an electrical cord under a carpet, as the wires can wear through. CAUTION: NEVER PLAY NEAR OR ENTER A PLACE WHERE THIS SIGN IS DISPLAYED. WARNING: THE VOLTAGE OF MAINS ELECTRICITY FROM THE WALL SOCKET IS HIGH ENOUGH TO KILL YOU! Topic 12: Energy and movement Unit 1: Stored energy Vocabulary elastic - a material that returns quickly to its original shape after it has been bent or stretched twist to wind something around or through an object compress to squash something and make it flat release to let something go

10 10 Elastic bands and springs Elastic bands and springs are used to move things. Before things are able to move we will either have to twist or stretch it. When we stretch or twist it, we give it the energy to make it move. When we release or let go of the elastic band, the stored energy is changed into movement energy. The same thing happens with springs. When we compress or squash a spring and let it go, it moves. We give the spring energy to move when we compress it. Releasing the spring allows the stored energy to change into movement energy. Topic 13: Systems for moving things Unit 1: Wheels and axels Vocabulary system two or more parts that work together for a common purpose or function mechanism parts of a machine that has a particular job to make a machine work axle a rod attached to a wheel and that goes through the middle of the wheel fulcrum the centre point on a wheel turning axle an axle that turns when the wheels turn fixed axle an axle that does not move; the wheel turns on the axel

11 A system is something that is made from two or more parts that work together to carry out a function. 11 Example: Frame + wheels + pedals + brakes + seat + gears = bicycle Many vehicles are systems with different parts that work together. Each moving part or mechanism does a special task to help the vehicle move. The most important system of mechanisms in a vehicle is the wheels and axles. The wheel and axle is a simple system made of a wheel attached to a rod. The rod is called an axle. The axle goes through the middle of the wheel. The wheel acts as a lever rotating around the fulcrum or the centre point. fulcrum In early vehicles, the axle was a pole of wood that fitted in the centre of the wheels. When the wheels turned, the axle also turned. We call this a turning axle. Most wheels today have fixed axles. This means that the axle does not move, but the wheels spin on the axle. Did you know...? Space travel would not have been possible without the invention of the wheel.

12 12 Long ago Today Bibliography: Platinum Natural Sciences and Technology- Maskew Miller and Longman Day by Day Natural Sciences and Technology- Maskew Miller and Longman Thunderbolt kids Natural Science and Technology- Dept of Basic Education