# Science Master Special – Hardness List

List of materials

wood (balsa)
wood (oak)
plastic object
bath sponge
china(cups and saucers)
glass
concrete pathway
cardboard
metal fork
coin
rock (sandstone)
piece of coal
pencil rubber

My hypothesis (idea ) is that the hardest material will be the metal. I have decided to test this by using a metal nail and trying to scratch all the samples on the list. The ease of the scratch will be linked to the softness of the material. These are the results of my test from softest to hardest.

bath sponge
cardboard
pencil rubber
Balsa wood
plastic object
wood (oak)
rock (sandstone)
piece of coal
concrete pathway
coin
metal fork
china (could not scratch)
glass (could not scratch)

Like to add some more examples …let me know by using the Reply Box.

# Science Master Special A Push-Pull Meter

Many years ago I and my class made a Push-Pull Meters with dowel rod and a cotton reels and had great fun with them, measuring all sorts of pushes and pulls.OK we could have used conventional force meters, the school had enough of them for class use, however making one yourself and then using it seems to make a big difference in understanding.

A recent question made me look for my plans – no chance. Search the internet – no luck. My team were of no help so I therefore decided to do the obvious thing, make one myself.

These are the drawings of my endeavours. The equipment list is cotton reel (wooden would be nice but if it’s plastic ok), a length of dowel rod with a diameter which will allow it to pass through the central hole of the cotton reel, an elastic band (probably 4 cm long but have a set of them for experimentation), a paperclip which is opened up to make a hook, some drawing pins or sellotape …….and I think thats it.

Once constructed the next task it to calibrate it. If you have access to a set of weights, great. you can create a little bag which will hold them, hang it on the hook and away you go. A 1kg mass will apply a 1 Newton force on the elastic band. This is where the choice of the elastic band is important – a thin band is obviously much more sensitive than a thick band. On the other hand, why not make up your own scale of push a pulls – a five marble/ 3 marble/1 marble push or pull. Below are the images that I created for my answer to the 10 yr olds question.

# Science Master Special – Energy

Thanks team. I would like to add a few things.

Firstly the list of different types of energy is not complete. If you can think of some more then ‘Leave a reply’ in the box below.

Secondly it is interesting how the energy conversions can take place. For example a microphone converts sound energy into electrical energy and a loudspeaker does the reverse process, it converts electrical energy into sound energy. Can you think of other examples?

# Science Master Special – atoms, molecules, intra and inter molecular forces, heat energy and kinetic movement

There is a bit of everything in the title. Maybe the basis of everything as we know it up to now.

• Atoms are the foundation of our understanding of matter (all the stuff around us).
• Molecules are the the building blocks that are constructed from atoms to build the stuff around us.
• The forces between atoms that make up the molecule are called intramolecular forces.
• The forces between the molecules that the atoms make are are the intermolecular forces.
• The study of molecular kinetics is the study of the movement of particles and the movement is usually associated with applied heat. Heat energy and movement are strongly linked. Heat something and it moves faster.

For a more detailed look at the structure of atoms look at this Science Master Special

Any questions?

# Science Master Special – What might plants need to grow?

1. Air (Oxygen and Carbon Dioxide)
2. The Sun or some light or maybe some darkness.
3. Warmth (heat), or maybe some coolness.
4. Water (moisture, dampness)
5. Soil, rocks, compost, sand.
6. Time, lots or maybe little.
7. Creatures, in or above the soil. These could be giant worms or miniscule creatures.
8. Plant food. Fertilisers, minerals.

This list was helped by The Nuffield Space Project P77

# Science Master Special – the Bernoulli effect (Flying)

Blowing through two pieces of paper results in the two pieces of paper coming together. The same can be done with two balloons. Hold two inflated balloons in front of your mouth and blow between them. You will be surprised.

The question is why does this happen? Bernoulli in 1782 looked at a similar phenomena using water and blood. He discovered that when blood  moved faster it applied less pressure on it’s surroundings. I have tried to illustrate this phenomena in the form of an animated GIF (there are some great free animated GIF builders online)

As I have said before the air is FULL of particles/molecules which are so small you cannot see them. BUT you feel them all the time. Try running holding a great sheet of cardboard in front of you, feel the wind blowing on you. Air molecules are constantly banging into you and everything around you. This is normally called ‘air pressure’. It’s the push of air on you and the two pieces of paper that you might be holding in front of your mouth.

Bernoulli in his work found that if you increase the speed of the, already moving , molecules they hit things around them less frequently and therefore less push means less pressure. I have tried to illustrate this in the animation above.

In an aeroplane as it moves through the air that goes over the top of the wing speeds up compared to the air underneath the wing. Look at a cross section of the shape of a wing. The push of the air on the bottom of the wing is therefore greater than the push of the air on top of the wing. Thus lift.

# Science Master Special – States of Matter (a role play)

This is a role play which I think can give you younger learner some ideas about the connections between solids liquids and gases. Try it with some friends.

There are only two roles: (1) The Director (2) The actors or water particles (molecules).

What is needed:  (1) Space to act out the role play (2) Temperature prompts for the Director [-15oC, -10oC, 0oC, 10oC, 30oC, 50oC, 80oC, 100oC]

To start the temperature is -15oC. The water particles are stationary (frozen) connected to each other by bonds (Hydrogen bonds-see below). The actors depict this by holding hands with the the other actors.

At -10oC the crystalline bonding is still holding BUT the molecules are slowly vibrating but still remaining in the same place.

As the temperature approaches 0oC things start to happen. The water molecules begin to move, slowly. The actors are not holding hands but have some contact with each other. The hydrogen bonding is still there.They can move from one molecule to another but must never lose contact …moving slowly. They are now liquid water molecules.

The temperature slowly increases and as it increases the water molecules are getting more and more energy from the heat source and begin to move faster. They are moving faster BUT still in contact with other water molecules. At 30oC one or two of the water molecules break away and then come back again.

At 50oC one water molecule escapes completely and doesn’t return. The rest are moving even faster.

At 80oC several molecules break away and maybe one returns. At 100oC the whole group begins to break up and move into the room they are now water vapour molecules and not connected at all to each other.

Hydrogen Bonds

The water molecule is an interesting particle. It consist of a central Oxygen atom and two Hydrogen atoms connected to it. The structure gives the Oxygen atom a small negative electrical charge, the Hydrogen atoms have a small positive charge. This means that the Hydrogen atom of one molecule of water can be attracted to the negatively charged Oxygen atom of another water molecule. This is your Hydrogen Bond.

# Science Master Special – Measuring the height of a tree using a pencil and a friend

Now and again I will mention some magical experiences.

This  was a technique given to me by a teacher at Severne Primary School in Birmingham.

Do you want to measure the height of a tree and all you have is a friend and a pencil?

First task line up the vertical pencil with a tree.

Second task get a friend to stand at the base of the tree.

Third task. Make the tree fall over. Not really, just make the pencil fall over.

Fourth task. Ask the friend to walk from the base of the tree to the end of the pencil, counting her/his steps. Shout stop when he/she reaches the end.

Fifth task. Work out the height of the tree. A step is about  60cm. You might need to check this with your friend, what is his /her step distance.

So what is the height of the tree? Any answers…..click on the ‘Leave a Reply’ and leave an answer.