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What was candle wax originally made from?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
Define the term ‘axle’
A rod attached to a wheel
Define the term ‘fulcrum’
Centre point
Define the term ‘turning axle’
A system in which the axle turns together with the wheels
Define the term ‘fixed axle’
A system in which the axle remains fixed while the wheels rotate around it
Provide an example of a system.
A bicycle. It is made up of more than two parts that work together to move someone from one place to another. The source of energy for this system comes from the person using it.
What does a system that moves vehicles consist of?
- Different parts that work together.
2. Each moving part is a mechanism with a specific job to help the vehicle move
Which mechanisms are the most important in a vehicle?
Wheels and axles
Describe the wheel and axle system.
- It is a simple system that is made of a wheel attached to a rod.
- The rod is called an axle.
- The axle goes through the middle of the wheel.
Example: the wheel of a car.
Explain how the wheel and axle system of a car works.
- The axle joins the wheel to the car and holds the wheel upright.
- The wheel and axle on a car tyre acts as a lever rotating around the fulcrum or centre point.
- The wheel moves when the lever rotates around the fulcrum.
Give three examples of systems that have wheels and axles.
- Cars
- Ferris wheel
- Wheelbarrow
Why is the wheel and axle system one of the most important inventions of all time?
Without wheels and axles, we would not have vehicles like cars and trucks for transport.
When were wheels first used?
5000 years ago
What were the first wheels like?
- The wheels and axles were made out of solid wood
2. They were very heavy.
How did the first wheel and axle systems work?
Both wheels were fixed onto the axle and the axle turned with the wheels.
How do newer wheels and axles work?
The axle is fixed to the vehicle and the wheels turn around the axle
What did people do to make the first wheels lighter?
They began to carve pieces out of the wooden wheels. The pieces they left behind were called spokes.
What was the disadvantage of lighter and thinner wheels?
They were damages more easily.
How did people protect their lighter and thinner wheels from damage originally?
- They began to cover the wheels with leather, iron, and later rubber.
- Today these covers are known as types.
When was the first air filled tyre used?
1888
What type of vehicle used the first air filled tyre?
A bicycle
What type of wheels do we use today?
Wheels with steel discs that are both light and strong.
Have we now perfected the wheel? Explain why you say so.
No, as new materials are developed that are even lighter and stronger, wheels are being improved to this day.
What type of axles did early vehicles have?
Turning axles
Why don’t we use turning axles on vehicles today?
Because when the vehicle turns, one set of wheels is dragged and this can cause the vehicle to fall over.
What type of system replaced turning axles?
Fixed axles
Why are fixed axles used in vehicles today?
When you turn a vehicle with a fixed axle, the inside wheel can turn more slowly while the outside one speeds up. Thus your vehicle won’t fall over.
What type of energy does wheels and axles require to move vehicles forward?
Input energy that can be transformed into output energy that in turn creates movement.
Where does the input energy of a bicycle come from?
The person pedaling the bicycle
Where does the input energy for a car come from?
The liquid fuel we place in the fuel tank. Either petrol or diesel.
Define the term ‘orbit’
The path of one object in space around another, such as the path of the earth around the sun
Define the term ‘revolution’
The movement of an object in space around another object, such as the movement of the the earth around the sun
Define the term ‘axis’
An imaginary line passing through the center of an object
Define the term ‘rotation’
The movement of an object around itself, such as the movement of the earth around its own axis.
What is the earth’s orbit?
The pathway in which it travels around the sun.
What is the difference between the orbit and the revolution of earth?
We call it a revolution because the earth moves around the sun. We use the term orbit to refer to the specific path that the earth takes while it moves around the sun.
In which direction does the earth move around the sun?
Anti clockwise
What does anti clockwise mean?
It means that you move in the opposite direction to that of the hands of a clock.
What does clockwise mean?
It means that you move in the same direction as the hands of a clock.
How fast does the earth travel in its orbit?
- 108 000 km per hour
2. 30 km per second
How long would it take to travel from Cape Town to Johannesburg if you could travel as fast as the earth travels in its orbit?
47 seconds
How long does it take the earth to complete one revolution around the sun?
365 days
How do we determine the length of a year?
A year is the same amount of days as it takes the earth to complete one revolution around the sun. 365 days for each
Why can the earth be found in different places at different times of the year?
Because the earth is constantly moving at 30km per second in its orbit around the sun. An object that keeps moving will keep changing its position.
Where is the axis of the earth located?
It runs through the centre of the earth from the North Pole to South Pole.
(Remember the axis is just an imaginary line, it is NOT a real line that you could go and look at)
What does the earth do with its axis?
- It turns around on its axis.
- So it turns round and round and spins and spins on its axis.
- So we say that the earth rotates around its axis.
(This is similar to how a wheel turns around an axle, don’t confuse the two concepts Chloe)
In which direction does the earth rotate around its axis?
- Anti clockwise
2. From west to east
How long does it take the earth to spin around its axis once?
24 hours thus it completes a rotation once a day.
Why don’t we feel the movement of the earth spinning around its axis?
We don’t feel the movement of the earth spinning so fast because we travel along with it.
Define the term ‘crust’
The hard, rocky layer on the surface of the earth
Where is the crust of the earth located?
The crust is everywhere around earth, even under the water of the oceans.
What are oceans?
- Huge areas of the earth’s surface that are covered in water.
- The oceans are lower than the continents
- They are like huge basins that have filled up with water.
How do we know that the earth’s crust is made of rock?
- We know because we have dug deep mines into the crust.
- We have drilled for oil under the sea
- Wherever we dig or drill, there is rock
- In some places the rock is covered by water and in others by soil but underneath the water and soil there is ALWAYS rock.
What does life on earth depend on to survive?
- Soil
- Air
- Water
- Sunlight
What do plants use to make their own food?
- Nutrients and water in the soil
- Carbon dioxide from the air
- Sunlight
Why do plants need to make food?
Because plants would not be able to survive and grow without the food they make.
Why do plants need soil?
- To extract nutrients for making food
2. To anchor their roots in the ground
Why do animals need air?
Because air has oxygen that animals need to breathe in
Why do animals need water?
To drink so they can stay alive.
Where do animals get their energy from?
- They get the energy they need for their life processes from the food they eat.
- This energy passes up the food chain from plants so all animals depend on plants for food.
- As a result animals also depend on soil, air, water and sunlight that plants use to make food
Define the term ‘topsoil’
The layer of soil that lies on the surface of the earth
Define the term ‘decompose’
To break down into smaller parts.
Define the term ‘fertile soil’
Soil in which plants can grow well
Define the term ‘subsoil’
The layer of soil that lies underneath the topsoil
Name two layers of soil
Topsoil
Subsoil
What colour is topsoil?
Topsoil is dark in colour
What does topsoil contain?
It has the remains of dead plants and animals in it that have decomposed.
What happens to topsoil when a body decomposes in it?
- The body breaks down into the smaller parts it is made of
- Nutrients from this body go into the soil.
- This makes topsoil the most nutrient rich layer of soil in which plants can grow best.
- Thus topsoil can also be called fertile soil.
What does the word ‘sub’ mean?
It means under.
Where is the subsoil located?
Under the topsoil.
What happens to subsoil when it rains?
Nutrients from the topsoil are washed down into the subsoil.
Is the subsoil useful to plants? How?
Yes, plant roots can get nutrients from the subsoil layer, although it is not as nutrient rich, or fertile as topsoil.
What lies beneath the subsoil?
Below the subsoil is a layer of broken pieces of rock, mixed with some soil.
What lies beneath the layer of broken rock and soil?
The solid rock of the earth’s crust. Soil is still forming here.
How does soil support life?
- Soil is the habitat of many different animals, like the aardvark
- Soil provides plants with nutrients and water so the plants can provide food for animals
Why will there always be solid rock beneath the topsoil on the surface?
Topsoil forms as rock on the surface of the earth that breaks down into smaller and smaller pieces so there will always be solid rock underneath that hasn’t been broken down yet.
How are rocks near the surface broken down into smaller pieces to become topsoil?
- Rock near the surface is in contact with water and air
- Chemicals in the water and air cause this rock to weaken and crumble
- The roots of plants growing in cracks in the rock also help to widen the cracks and break the rocks down into smaller and smaller pieces
- Dead plant and animal matter mixes with the rock
- Slowly topsoil forms on the surface
How is the subsoil formed once the topsoil exists?
- The rock below the topsoil begins to break down as water, air and plant roots can move down through the topsoil to reach it.
- Slowly, over millions of years, this rock changes into soil and the soil on the surface of the earth gets deeper
- As the soil gets deeper the subsoil is formed.
Define the term ‘microscope’
An instrument that makes small things appear much bigger
Define the term ‘coarse grains’
Large soil grains
Define the term ‘fine grains’
Very small soil grains
Define the term ‘soil grains’
Small pieces of broken rock
Define the term ‘humus’
Dark material in the soil made of fully decomposed remains of plants and animals
Define the term ‘eroded soil’
Soil that has been washed away by water or blown away by wind
Define the term ‘clay grains’
Soil grains that are so small that you cannot see them unless you look at them through a special microscope.
(Also known as fine grains)
Name the three main types of soil.
- Sandy soil
- Clayey soil
- Loamy soil
On what does the division of soil into three main types depend?
It depends on the amount of coarse grains compared fine grains in it.
Describe sandy soil
- Sandy soil is soil in which there are more coarse sand grains than fine grains.
- Sandy soil feels gritty when you rub it between your fingers.
Describe clayey soil.
- Clayey soil has more fine grains of clay than coarse grains of sand.
- If you rub dry clayey soil between your fingers it feels smooth
- Wet clayey soil feels sticky and will hold a shape
Describe loamy soil.
- Loamy soil is a mixture of equal amounts of clay, sand and other soil grains
- It also contains humus.
- The humus makes the loamy soil light and nutrient rich
- Plants grow best in loamy soil
What does humus look like?
Humus is light in weight and dark in colour
What does humus consist of?
- Humus consist of fully decomposed plant and animal remains.
- If you can still see bit of twigs and leaves in it, it is still compost and not humus yet.
How does soil have air and water in it?
- The grains of sand and clay that soil is made of do not fit neatly together
- There are spaces between the grains that can hold water and air
Why can clayey soil hold water better than sandy soil?
- Clayey soil has small spaces between the grains of clay, but lots and lots of these tiny spaces
- Sandy soil has large spaces between the grains of sand but does not have as many spaces.
- Overall, there is more space for water in clayey soil than in sandy soil.
Why does clayey soil remain wet longer than sandy soil?
- Water passes very easily through the large spaces in sandy soils
- But slowly through the small spaces in clayey soil
- Sandy soil is therefor often dry soon after rain
- While clayey soil remains wet for longer
Why do plants prefer loamy soil over clayey and sandy soil?
- It is rich in nutrients
- It is a mixture of coarse and fine grains
- Loamy soil does not get too wet or too dry
What types of larger animals live in the soil?
- Meerkat
- Aardvark
(Both dig burrows)
What types of small animals live in soil?
- Earthworms
- Termites
- Crickets
- Spiders
How does animals living in the soil benefit plants?
- These animals all help to mix the soil up.
- Their movement takes material lying on the surface, like dead leaves and animal bones, into the soil
- As small animals move through the soil, they open up spaces for more air and water in the soil
- This makes it easier for plants to grow
Other than animals, what else lives in the soil?
Millions of different kinds of very tiny living organisms that you can only see under a microscope
What is the function of tiny soil organisms?
- They feed on the remains of dead plants and animals
- This causes the dead plants and animals to decompose
- Once they have done this the larger animals mix the compost with soil to spread the nutrients around to make the soil fertile
How can topsoil be destroyed?
- It can be washed away by water
- It can be blown away by wind
- When this happens we call it erosion
Why can’t we replace topsoil once it is lost?
Because soil forms very slowly over thousands of years.
Why is it important to conserve our soil?
Because all life depends on the plants that grow in nutrient rich soil.
Define the term ‘sedimentary rock’
Rock that forms when sediments are deposited in layers and harden
Define the term ‘deposit’
Drop or put down in a certain place
Define the term ‘sediments’
Soil and pieces of broken rock deposited by a river or by the wind
Define the term ‘compact’
Press together tightly
Define the term ‘shale’
A kind of sedimentary rock made from clay
Define the term ‘sandstone’
A kind of sedimentary rock made from sand
Define the term ‘limestone’
A kind of sedimentary rock made from the shells and bones of tiny sea animals
Name the 5 steps in the formation of sedimentary rock
- Rock breaks down into small grains
- Mud and sand are moved by wind and water
- Mud, dust and sand are deposited in low lying areas
- New layers of mud and sand are deposited on top of existing layers
- The layers become compacted and hardened, and form sedimentary rock
How can sand and mud be moved by wind and water?
- Fine grains of clay form dust when they are dry and mud when they are wet
- Dust and sand can be blown away by the wind
- Sand and mud can also be washed away by water flowing over the surface of the earth after it has rained.
- They are carried down to a river
When is sand and dust deposited?
When the wind slows down or stops blowing, the sand and dust is deposited in a low-lying area
When is sand and mud deposited?
- When the river slows down it deposits its load as it flows over a low-lying area near the sea, and when it enters the sea or a large lake
Do water and wind deposit their loads randomly? Explain your answer.
No, they always deposit sediments in the same places over and over again, adding new layers over the old layers
How long does it take to build up thick layers of sediment?
Millions of years
Why do layers of sediment become compacted?
- Over time, the weight of the top layers presses down on the layers at the bottom.
- The grains of sand and mud in the bottom layers become tightly packed together and thus we say they are compacted
- The compacted sediments are hard and form sedimentary rock
Name 2 characteristics of sedimentary rock.
- You can always see layers in sedimentary rock
2. The layers are not always the same thickness or colour
What is sedimentary rock made from mud called?
Shale
What is sedimentary rock made from sand called?
Sandstone
Does limestone form from pieces of broken rock?
No.
What is limestone formed from?
It is made from the remains of dead sea animals.
How is limestone made?
- Shells and bones collect on the sea floor and over time harden into a layer of rock.
- Most of these animals are very small and their remains are so broken down that you cannot see them in the rock
What is cement?
Cement is a grey or white powder that is used in many ways in the building industry
What is limestone used for?
- Cement is made from limestone
- The limestone is crushed and mixed with small amounts of clay
- The mixture is heated to almost 1500°C in a special oven called a kiln.
- The powder is then packed in bags
Where can shake and sandstone be used?
1.In buildings as building blocks, bricks or tiles
How do you turn shale into bricks?
- Ground the shake up finely
- Mix the powder with water to make clay
- Shape the clay into a brick and bake it to harden it again
Define the term ‘fossil’
The remains or signs of ancient plants and animals preserved in rock
Define the term ‘ancient’
From a very long time ago
Define the term ‘preserved’
Did not rot away
