Natural Science Flashcards
Define the term ‘stored energy’.
Stored energy is energy that is stored in something like food or fuel. It can be changed.
Define the term ‘fuel’.
Fuel is a substance that can be eaten or burned to produce energy.
Define the term ‘input energy’.
Input energy is the energy we need to ‘put in’ to start a fuel burning.
Define the term ‘output energy’.
Output energy is the energy such as heat and light energy, that is produced when a fuel burns.
What does our bodies use energy for?
- Walk
- Run
- Play
- Any physical activity
Where do our bodies get energy from?
Our bodies get energy from the food we eat.
Name some activities for which we need energy from fuel.
- Cooking
- Light
- Heat
- Travel
What is stored in fuel?
Energy
Where do plants get their energy from?
From the sun
Why is food called fuel for the body?
Because food contains stored energy.
What do plants use the sun’s energy for?
To make its own food.
Where do plants store their food?
- Leaves
- Stems
- Fruit
How long does energy stay stored in plants?
Until the plant is eaten by a person or animal.
Name 5 examples of fuels.
- Wood
- Coal
- Natural gas
- Paraffin
- Candle wax
- Beeswax
- Petrol
What can the stored energy in fuels like coal, gas and paraffin be used for?
- Heating our homes
- Lighting our homes
- Cooking our food
What was candle wax originally made from?
Beeswax or various plant waxes
What is candle wax commonly made from today?
Paraffin wax
How is the energy stored in candle wax used?
- The energy is used up as the candle burns.
2. The energy is used to make light and some heat.
What type of fuel is petrol?
Petrol is a liquid fuel.
What uses petrol?
Cars and taxis
How do vehicles store petrol?
They store petrol in their petrol tank.
How does a car use petrol?
- The petrol is burned in the car’s engine,
- This creates heat energy,
- Which makes the engine work,
- Which makes the car move.
Provide an example of input energy.
A candle needs a burning match to set its wick alight.
Do all fuels need the same input energy?
No, different fuels need different amounts of input energy
Provide two examples of fuels that require small amounts of input energy.
- A paraffin lamp
2. A candle
Provide an example of a fuel that needs a large amount of input energy
Wooden logs for a fire
What do we use to light wooden logs?
Firelighters
What is a firelighter?
- A firelighter is a substance that burns easily
2. And is used to start fires.
What happens when fuels start burning?
- The stored energy inside the fuel is released,
- And changed to other forms of energy,
- Like heat and light
Provide an example of output energy.
When petrol burns in a car engine, the stored energy is released and that output energy is used to make the car move.
Define the term ‘prevent’.
To prevent is to keep something from happening
When are fires useful?
When they are controlled fires
How can controlled fires be useful?
- To cook food
2. To provide heat
When are fires harmful?
When they are not controlled.
How can uncontrolled fires start?
- They start by accident from a lighting strike
2. Or when a controlled fire gets out of control.
What harm is caused by uncontrolled fires?
- They harm plants and animals,
- They damage property
- They put people’s lives at risk
Who stops fires?
Specially trained firefighters
Name five ways to prevent fires.
- Do not play with matches or lighters
- Do not pour any fuel like petrol or lighter gel onto a burning fire
- Use sturdy candle holders and keep candles away from anything that might catch fire.
- Place firegaurds in front of fireplaces
- Do not dry clothes near a heater or cooker
- Never leave the stove on and alone
- Make sure your fire is fully extinguished when you are done
- Don’t use damaged electrical appliances
What actions should you take during a fire?
- Stay calm
- If there is smoke, stay low on the ground
- Crawl away from the fire
- Make your way to the nearest exit
- Get out of the building as soon as you can
- Call the fire station
Why should stay low during a fire?
- Because the poisonous gases in smoke can hurt people more than the actual flames.
- Keeping low allows you to breathe in less smoke.
What is electricity?
Electricity is a type of energy
Why do we need electricity?
- It provides the input energy that machines and appliances need before they can produce output energy that is useful to us.
- Electrical appliances need electricity to work.
What types of output energy is produced by electricity?
- Light
- Sound
- Heat
- Movement
What types of energy can be changed into electricity?
- Sunlight
- Water
- Coal
- Chemicals
Define the term ‘electricity box’.
The place where electricity from a substation is connected to the electrical circuits in a building.
Define the term ‘wall socket’.
The part of the wall where an electrical appliance can be connected to an electrical circuit
Define the term ‘plug’.
The part of an electrical appliance that can be connected to a wall socket.
Define the term ‘turbine’.
A rod that turns, with blades arranged like a wheel around it
Define the term ‘generator’.
A machine that produces electricity.
What type of electricity do most appliances in our homes use?
Mains electricity
Where do we get mains electricity from?
A very big electrical circuit called the national grid
What is the national grid?
A system of wires and cables takes the electricity from a power station to people’s homes, schools and workplaces
How does the electrical energy change as it goes through the mains system?
- Some of the electrical energy changes into heat as it travels along the cables.
- Electrical appliances also change some of the electricity into other types of energy.
Name the four parts of a mains electricity system.
- Power station
- Pylons and transmission lines
- Substations
- Places where electricity is needed
Where does mains electricity come from?
A power station.
What source of energy is mostly used in power stations in South Africa?
Coal
What are transmission lines?
They are thick metal cables through which electricity goes from a power station to a sub station.
What is the purpose of a pylon?
A pylon is a big tower that supports the transmission lines.
What is a substation?
A substation is a place where the strength of the electricity is changed to make it either stronger or weaker.
Why is electricity made stronger at some substations?
So that it can travel long distances through transmission lines.
Why is electricity made weaker at some substations?
It is made weaker so that it is safe to use in homes, shops and other places.
How does the electricity get from the substation to the places where it is needed?
From the substation, underground cables or overhead wires take the electricity to people’s homes, shops and other places.
How are buildings connected to mains electricity?
The building usually has an electricity box where the wires from the substation are connected to the electrical circuits in the building.
What is an electricity meter?
It is a meter that records the amount of electricity used.
What is a trip switch?
It is a switch that trips the power when there is safety risk.
Name the components of an electricity box.
- Wires from the substation
- Electrical circuits from the building
- An electricity meter
- A trip switch
Where are the electrical wires and circuits located in a building?
In the walls or in the ceiling
What are the electrical circuits of a building connected to other than the electricity box?
- Lights
- Switches
- Wall sockets
Where does the electricity go when an appliance is turned on?
The electricity goes from the wire in the wall to the appliance.
What is the purpose of a power station?
It changes energy into electrical energy.
Name the different types of energy used by different types of power stations to create electricity.
- Coal
- Falling water
- The wind
- Heat from the sun
What happens in a coal burning power station?
- Coal burns in a boiler and it gets very hot.
- The heat changes water into steam.
- The steam turns a turbine.
- The moving turbine turns a generator. The generator changes the movement energy from the turbine into electricity.
- The electricity goes into the transmission lines. These connect the power station with the places where electricity is needed.
Discuss the disadvantages of burning coal in power stations.
- It produces gases and very small particles of ash that go into the air. 2. These cause air pollution and can affect people’s health.
- Mining coal is dangerous to people’s health and damages the environment
How many nuclear power stations does South Africa have?
One.
What type of nuclear fuel is used in South Africa?
Nuclear fuel made from uranium.
What is the advantages of using nuclear power stations?
No gas or smoke is produced.
What are the disadvantages of using nuclear power stations?
- They produce dangerous nuclear waste.
- This waste must be protected from people and the environment sometimes for thousands of years.
- Mining uranium damages people’s health and the environment
Why is electricity dangerous?
- If electrical wires and appliances are damaged or not connected correctly they can cause fires
- They can also give people electric shocks.
- If a lot of electricity goes through a person’s body, the person may die of shock.
Name 3 important facts about electricity.
- Electricity transmission lines and wires in substations carry large amounts of electricity
- Electricity does not go through plastic and rubber,
- Electricity easily goes through water, people’s bodies and metal.
Discuss 5 ways to use plugs and wall sockets safely.
- Do not plug too many appliances into one wall socket. It can cause a fire or overload of the system.
- Make sure that the switch is off before taking a plug out of a wall socket
- Hold the sides of a plug to remove it from a wall socket, do not pull it by the cord
- If a wall socket is not used, make sure the switch is in the off position
- Wall sockets are only for plugs. Do not put your finger or a wire into the holes in a wall socket
What is an electrical cord?
Electrical cords are made with thick plastic that covers the metal wires that carry electricity
How can you use electrical cords safely?
- There should be no metal wires showing on the cord from the plug to the appliance
- Do not use damaged cords, get an adult to replace them
- Heat can damage the plastic coating on the cord so keep them away from hot surfaces
- Do not put electrical cords under carpets or rugs, or through hinges or the back of doors
- Do not mend or join broken cords with tape.
Do not put electrical cords where a person can trip over them.
Discuss electrical safety with water.
- Never use an electrical appliance near water, especially in the bathroom. Don’t use an electrical lawnmower on wet grass.
- Never touch an electrical appliance with wet hands
- Unplug an electric kettle or iron before putting water in it
- Never use water to put out a fire close to, or in, an electrical system. Use sand or dry chemical fire extinguisher instead
Discuss the safety rules for electricity outside the home.
- Stay out of electrical substations
- Do not touch, or go near, any electrical transmission lines, even if they have fallen on the ground
- Do not play or make a fire underneath power lines
- Do not carry long objects underneath power lines
- Never climb electrical pylons
Define the term ‘system’
A system is two or more parts that work together to carry out a function
Define the term ‘mechanism’
Parts of a machine that do specific jobs to make the machine work