BuiltWithNOF
Air

There are all sorts of fun and interesting experiments and demonstrations we can do on this topic. I can’t believe that some people think there’s very little to it and not much to do or explain!!!

‘The air’ is a fantastic topic for a scientist because it involves lots of observations and investigations which lead to a ‘model’ which explains what air is and why it behaves the way it does.

Scientists often talk about a ‘model’ when explaining things which are invisible because they are too small, like atoms or living cells, or when things are too big, like the Universe! A model could be a solid object we can make with materials which represents how something looks or works, but it could also be simply an idea or picture in our imagination. A model is simply a way of thinking about something which is difficult to explain.

Put yourself in the position of an early scientist (‘Natural Philosopher’). They knew that humans and animals could breathe and could observe the motion of the chest as it seemed to fill up then empty. What was it filling up with? Why was this process necessary? Whatever it was, why was it essential to us?

After they had the chance to think about it, what did the early scientists believe it was?

We can’t see the air so how do we know it is there?

What is it made from?

Can we compare it with water? What are the differences?

Can we make air?

Is air just one thing or is it more than one?

Is it the same everywhere?

It allows us to live, but what else can the air do?

Has it always been here?

What if it started to disappear?

Do other planets have air or something similar?

 

Following is a series of pictures, demonstrations and things to try in order to find out more about the air and, hopefully, convince you that it is a real material. You can start by discussing the things happening in the pictures.

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When we look outside through the window how do we know if it’s windy? We can’t feel the wind indoors but we can see what the wind is doing and know that it is there! We can see the trees bending in the wind so they must be being pushed. The wind can give a FORCE that can push things over. The wind can: Knock your hat off; Turn your umbrella inside out; Lift a kite flier off the ground!

You can’t be pushed by ‘nothing’ so the wind must be made of ‘something’! What can it be?

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When we breathe we can feel our chests getting bigger then smaller. We can hear our breath as it passes in and out through mouth and nose. We can ‘see’ our breath on a cold day. It looks like a white cloud which quickly disappears. We can use our breath to speak, sing and play musical instruments. We always take a deep breath before starting to read out loud or sing. Another thing to do with our breath is to have fun blowing bubbles. The bubbles are a way to capture our breath inside some soapy water. The bubbles have size and shape because of our breath inside them stretching the bubbles as if it’s trying to get out!

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We need air to breath so that we can stay alive. We can only go under water if we hold our breath. How can these divers stay under water for so long? How can a fireman breath in a smoke filled building? Fish are living creatures and they need to breathe but how can they do this under the water? A whale or dolphin isn’t a fish, it’s a mammal (like us) and it needs to hold its breath under water. How long can a whale stay under water before it has to come up for air?

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If we drop a ball it falls straight down to the ground. We believe in the ‘Force of Gravity’ which is attracting us towards the Earth below us. A ball falls down to Earth in a straight line because it is being pulled downwards by gravity.
A leaf falling from a tree doesn’t fall in a straight line (even on a day when there is no breeze at all)! It still ends up on the ground like the ball but as it falls it tumbles and moves left and right. Something else must be pushing it with enough Force to make it move in a different way to the ball.
It is the air which is causing this to happen. As an object falls it is not falling through ‘nothing’, it is falling through a real material which we call the ‘air’. The air is being pushed out of the way by the leaf or ball but pushes back a little on them too! The ball is too heavy to notice the pushing of the air but the leaf weighs so little it can really feel the pushing Force enough to make it change course. The shape of the leaf affects the way it falls too. The ball is perfectly round so it experiences an even pushing force all over.
It wasn’t until 1969 that a wonderful experiment on the Moon helped us gather more evidence about objects falling to the ground. The astronaut Neil Armstrong dropped a feather and a hammer at the same time and watched them both fall in a straight line and land at exactly the same time. If we try this on Earth it doesn’t work and the hammer lands first! Why?

You can see the video of this amazing experiment on You Tube....

www.youtube.com/watch?v=5C5_dOEyAfk

The Moon has no ‘atmosphere’. The Earth is surrounded by a layer of air being held around it by gravity. We call this our ‘atmosphere’. It is a mixture of air and moisture (the water needed to make rain clouds). Since the moon does not have any atmosphere at all then things fall to the ground without being pushed and slowed down by anything on the way. All objects no matter how big or small, heavy or lightweight will fall at the same speed when dropped on the Moon.

Would a parachute work on the Moon? Think about how a parachute works on Earth. It slows down the descent of the skydiver because the air fills up inside the chute and creates a very large lightweight shape which has to push lots of air out of the way to allow it to fall. This means there is a large pushing Force from the air under the chute which slows it down even though it is being pulled down by gravity. We say that the parachute has lots of ‘drag’.
Now, what would happen on the Moon?

Parachutes have been used on the planet Mars! They have helped land special ‘rovers’ which take pictures and find out what Mars looks like close up. Mars has an atmosphere but it isn’t the same as ours. It is also much ‘thinner’ so gigantic parachutes have to be used - why?

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The photograph above left shows the Moon above the Earth. Look closely and you can see a faint band of light blue colour above the surface of the Earth and following the same curve. This is the Earth’s atmosphere. It spreads out around the Earth to a height of hundreds of miles but the part containing the air we breath and the clouds that give us rain is within 10 miles. In fact the air gets thinner and thinner the farther away from the Earth we go and this is why aeroplanes carry oxygen for us to breathe and also why mountaineers carry oxygen when climbing Mount Everest which is over 5 miles high!.
The picture above middle shows a space capsule returning to Earth. It is falling through the Earth’s atmosphere pulled by gravity but being slowed down by the air. In fact the air can rub against it so much that the underside of the capsule, which faces into the air, gets very very hot and parts of it are burnt away. It looks a bit like a firework as it speeds towards the Earth. When it gets close enough to the Earth and there is enough air, a parachute opens to slow it down and it splashes into the sea. The astronauts inside can then climb out - I’m sure they will want a nice cool drink after that experience!

Summary so far...

We can’t see the air which is all around us but we know it must be there because of the observations we make such as:

  • Living things such as mammals are seen to breathe in and out
  • We can feel the air against our skin when we blow air out through our mouths and into our hands
  • We can hear air rushing in and out as we breathe heavily during exercise
  • When we take a deep breath and hold it we feel our lungs inflate and chests get bigger
  • We can blow bubbles full of air using soapy water or when we breathe out under water
  • We see leaves tumble as the air pushes against them and slows them down on their way to the ground
  • We feel the Force of moving air when it is windy and our hats are blown off or when we fly a kite
  • A parachute can only work if there is something in it to fill it up and slow it down on its way to the ground
  • The hammer and feather experiment works differently on the Earth compared to the Moon because there is no air or atmosphere on the Moon.

Things to make, test and demonstrate

Flying fish and helicopters.
See how to make flying fish, spinners and helicopters at You Tube on the technologytom channel

http://www.youtube.com/user/technologytom

To make a simple flying fish you will need:

  • A strip of paper about 3cm wide and 21 cm long (a 3cm strip cut from the shorter side of an A4 sheet is ideal).
  • Fold in half to find the middle and draw a face.
  • Make two scissor cuts about 3cm from the ends but in opposite directions halfway through making sure not to cut anything off!
  • Join the two ends by bringing together the two scissor cuts.
fish
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If you are part of a group making flying fish then make sure to write your name on the fish or colour it in with a pattern you will recognize because when you test your fish it’s easy to mix them all up!
Test the fish by gently holding it out away from your body as high as you can and then letting go.
Instead of falling down to the ground in a straight line it spins round and round and travels off to one side as if it had an engine!

If you have a safe high place to release the fish from you will see it spin and spiral its way to the ground.

Now try making a smaller fish and a larger fish but keep the width the same for all and predict what you think will happen when you release all three at the same time. Then try it.

Which fish will land first and why? Think about the air, gravity and about how a parachute works.

Now try and make some different types of spinners. You can even have a competition to see who can design and make the spinner which takes the longest time to fall to the ground.

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This is a ‘simple spinner’ made from a strip of card and using a paper clip or some sticky tape to hold it together and give it some weight near the bottom

If you add a paper tube to the spinner you can make a fantastic ‘helicopter’. The paper tube acts as a weight so you don’t need the paper clip. It also acts as a holder to make it easy to support then release to try it out.

This is the best type of design to start with in a design and make project since the paper tube allows you to join and try lots of different shapes and sizes of helicopter ‘blades’ or wings. It’s amazing how long you can get the helicopters to stay in the air before they touch down!

Windmills

toy windmill

Toy windmill

kos windmill

Sail windmill in Greece

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Whitburn Mill in Sunderland

nissan turbines

Nissan Car factory wind turbines for making...what?

How can you make a windmill spin when there is no wind and without touching the sails?

You could simply blow against the sails to make your own wind! But, there is a simpler way - all you have to do is......?

Clue: Spinners and helicopters work without a wind blowing them. It is the air around them that causes them to spin as they move through it!

So all you have to do is walk with the windmill held out in front of you. Try it and then try and explain what is happening.

 

The ‘blades’ or sails of a windmill are very similar to the wings of the helicopters and spinners. Their shape allows them to ‘scoop’ the air and push against it. The wind is simply air that is moving. The wind is made when air gets heated by the Sun and starts to rise up. It pushes cold air out of the way and starts enormous ‘currents’ of air moving around the Earth. The spin of the Earth also affects the winds. The blades or sails of a windmill catch the moving air and because the blades are fitted to an axle in the middle which can move, this causes the blades to spin. Because the blades are so big they can receive an enormous pushing force from the wind and can be made to turn very fast and with great power. Windmills were used thousands of years ago to power machinery to grind wheat to make flour. Some old fashioned windmills like Whitburn Mill kept on working until about 1900 and then were replaced by steam powered and electric machines to grind wheat.

The Nissan car factory turbines are electricity generators. The power of the wind is used to make electricity. The electricity is used to power the machines in the factory which make the cars.

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Here are some amazing experimenters and inventors from Stobhillgate First School in Morpeth trying out Wind turbines which are making electricity. They are running up and down the yard with their wind turbines and storing the electricity they make in small batteries.
They are trying out different sizes, shapes and numbers of blades to see which design makes most electricity.

Hand held fan

battery-operated-fan-1[1]

This is a battery operated fan used to cool us down on a hot day by blowing air towards us. The shape of the fan blades is just like some types of windmill blades and is similar to the ‘angled’ blades of the helicopters and spinners.
As the blades spin they scoop the air and push it towards us making their own wind.

A windmill and fan are really the same thing but doing the opposite job. Try describing the different jobs they do and how they do it.

Beachball

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It sounds silly but why does the beachball on the right bounce but the one on the left doesn’t?

How can we make the one on the left bounce?

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A ball like a beachball, football or tennis ball bounces because of the air inside it. When the ball strikes something the air inside starts to squash together because it is being Forced! The amazing thing is that it gets smaller when a Force is used to squash it then ‘springs’ back to its normal size and gives a pushing Force which makes it bounce.

A ball bounces because of the springiness of the air inside it.

It’s easy to see that a metal spring is made from a real material. We can see it, touch it and feel its weight. I think it is amazing that we can’t see the air and can only feel it when it is moving (as in the wind) but it can behave just like a strong metal spring. In fact air is used in car suspension to give us a springy smooth ride! Air is a real material and has special properties or characteristics like all materials.

Car and bicycle tyres work in the same way. They are pumped full of air which becomes all squashed up. When we hit a bump in the road the tyre squashes in then springs back out again to its original size. This helps give us a comfortable ride on the road.

Air in balloons

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Balloons and balloon pumps

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Balloons, party squeakers and tubes

Blow up a balloon using a balloon pump then let go!

As we blow more and more air into the balloon it gets bigger and bigger. We can hear the air ‘hissing’ its way in.

When we let go we can hear the rush of air as it escapes from the mouth of the balloon and we can see it fly around the room.

Why does this happen? Try to explain it using the word Force.

Why does the air not stay inside the balloon even though the mouth is open?

Remember, things will only move if a Force is involved so where is the Force coming from?

Another FORCE is at play in the case of a balloon. The STRETCHING Force in the skin of the balloon is what makes the air come out when we release the balloon. The stretched skin is also squashing the air inside and creating ‘pressure’. The Pressurized air rushes out when it is allowed and this means it can reduce the pressure - just like when a spring is allowed to relax back to its original size.

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A fun way to demonstrate the pushing power of compressed air is to attach a balloon to a plastic straw and run a thin string through the straw as a guide. Tie the string between two chairs or desks and make it tight so that it becomes horizontal.

Inflate the balloon and let go! It whizzes along the string really quickly. The ‘action’ is the force due to the air rushing out from the hole in the balloon. The ‘reaction’ is the opposing force which pushes the balloon forwards along the string.

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Toy rocket launchers are another good way to show how AIR, PRESSURE and FORCE are linked.
The launcher is simply two hollow tubes which neatly fit together and can slide apart. By opening them up fully we fill them with air from tip to toe.
The only place the air can escape is from the hole in the tip where the rocket fits.
When the two halves of the launcher are pushed together we are forcing the air inside to become ‘smaller’. We are trying to decrease the VOLUME of the air. In doing so we increase the PRESSURE of the air by making it squash together more closely.It can be compared to trying to squash too many people into a lift! As the PRESSURE builds up a large FORCE is created against the inside walls of the launcher tubes and at the tip where the rocket covers the hole. Eventually this FORCE becomes great enough to push the rocket off the end and fire it!

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There are lots of ways to make rocket launchers. A paper roll tube with a foam tip and card tail flights can fly very quickly and travel a long distance.

See the ‘Rockets’ page in the D and T section

These pictures show a paper roll tube rocket and two different types of launcher - an ordinary plastic milk carton and a garden spray pressure bottle.

The plastic milk bottle has a hole in the lid and a plastic tube fitted through which passes inside the rocket and allows air from the bottle to push on the rocket when the bottle is squeezed.

The pressure spray bottle has a switch (valve) which allows you to control the air a lot better.

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‘Pop-guns’ were popular Victorian toys. The one in the picture has been made from a bicycle pump and a white plastic tube sticky-taped onto it. A string attaches to a cork or plastic foam ‘bung’ which is a tight fit in the end of the tube.

Pushing on the bicycle pump increases the PRESSURE of the air in the white tube and causes a large enough FORCE to push the cork off the end making a loud ‘pop’ noise as it does so.

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Plastic syringes attached by a tube are a fun way to investigate changes in pressure.
Start with one syringe full of air and the other empty.
Push in the full one and observe the empty one.
There is a slight time delay as the air is pressurized and flows through the tube from the full to the empty syringe.
Can you think of any other things to try and can you explain them?

Try holding the empty one to prevent it from moving. You can feel a FORCE being exerted against your hand and when the full syringe is released it moves back out to its original position. This shows how air is ‘springy’ and a ‘cushion’ of air can support a heavy weight. It seems ridiculous to compare air which is a gas (mixture of gases) to a spring made from steel but the comparison is a good one and compressed air is often used in car suspension systems to raise the car chassis off the ground and give a comfortable ‘springy’ ride.

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The pressure spray bottle can be used in all sorts of experiments because it acts as a large source of pressurized air which can last a long time.

Care must be taken when using the pressure bottle because it can produce a large FORCE very suddenly!

Never point the open end of the tube at anyone - even the rush of air could cause an accident!

The jet of air can make a windmill spin very quickly and this illustrates how a machine called a TURBINE’ works. Turbines are used in power stations, jet engines on aeroplanes and even in dental drills and polishers!

Making a ping pong ball defy gravity is a fun thing to do using the jet of air from the bottle.
If you are careful you can support the ball in mid air using a jet of air pointing upwards even though gravity is pulling the ball downwards.

07AirMolecules[1]

All materials are made from tiny little pieces called atoms. Each atom is too small to see on its own but many millions of them together can be seen eg. like in a piece of metal, wood or plastic. In solids like metals the atoms are very close together and this makes metals quite heavy.

In gases like air the atoms are spread out and are free to move all over the place. Gravity holds the air around our planet and stops it from escaping off into space. Gravity can’t stop the atoms in air from moving about though!

Because atoms in gases are free to move around we can squash or stretch them by holding them in a container and using a FORCE. Squashing a gas makes the atoms get closer together and increases the PRESSURE of the gas. The gas atoms push back against the FORCE trying to squash them by speeding up and bouncing against the walls of the container! It’s as if they were angry!

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‘Atoms’ aren’t the whole story! There are different types of atoms eg. copper, oxygen, helium, gold etc.
The term ‘molecule’ is used to describe the smallest part (particle) of a material which is found naturally. Some atoms prefer to stay on their own as individuals so we say that the molecules of that material contain single atoms. Some atoms pair up or join with other different types of atoms to form more complicated molecules.
Can you spot molecules of.....
Nitrogen (written as N2 ), Oxygen (O2), Argon (Ar), Neon (Ne), Carbon Dioxide (CO2), Helium (He), Hydrogen (H2), Methane (CH4), Krypton (Kr), Xenon (Xe).

The picture of the molecules above is what we believe AIR is made from. It is a mixture of different gases: Mainly Nitrogen and Oxygen with very small amounts of the others.

There is also some ‘moisture’ in the air. Moisture is simply water (called water vapour) which comes from the seas, rivers, puddles and rain which slowly release their water into the air to mix with the other gases.

When we pressurize the air we are squashing many millions of these molecule closer together and making them bounce into one another very quickly.

Nobody has ever seen single molecules of the gases described above but we believe that they are there and behave in special ways because of all the things described above which can be observed and tried out by us and by the scientists who came before us.

Following soon...

Gases in water, fizzy drinks, coke and mentos fizzy fountain experiment.

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[Technology Tom] [2015 Eclipses] [Boxed Kits for sale] [Resources for sale] [INSET] [Science shows] [Science] [Materials] [Properties] [Vocabulary] [Materials Families] [I spy materials] [Investigating Materials] [Investigation proforma examples] [Different types of scientific enquiry] [Batteries or cells?] [Electricity 1] [Electricity 2] [Electricity 3] [Electricity 4] [Electricity 5] [Forces Investigations] [Friction] [Stretching] [Magnetism] [Vehicles] [Heat] [Cooling] [Insulators] [Conductors] [Spoons] [Light] [Space] [Design a planet] [Filtering] [Data-logging] [Foaming Volcano] [Reaction Time] [Energy] [Air] [Water] [Toys and Forces] [D and T Projects] [New Projects] [Try this] [Basic vehicle assembly] [MPD Diploma] [Workshops] [Libby] [Christmas Lecture] [queries page] [Raspberry Pi] [HMS Belfast] [Tree Houses] [Andrew] [Gainsborough Primary School] [Path Head Watermill]