“Why do spiders make webs and what are they made of?” asks Emily (7)

 

Thanks Team and thank you Emily. My first thoughts are about catching a spider and trying to keep it at home or somewhere else or finding a spider in the wild so that you can see it making, or looking after its web. I am however reluctant to suggest both catching a spider or keeping it in an indoors.

In some countries spiders can be dangerous so please do not interfere with it until an adult has identified it and  said that it is OK to collect it, or observe it closely.  If, with an adults permission, you can keep a spider then a large plastic aquarium would probably provide a good home for it.

A spider’s web is made of a type of silk, so ask an adult if they could find some silk for you to investigate. Maybe you could use it to make a web and see how strong it is?

If you do keep a spider, at home, or in the classroom you will have to decide how you will feed it. That will be an interesting investigation.

Look at this video of a garden spider building its web. In the first part of the video everything is slowed down. In the second part of the video things are at the real speed of web building.

Mason (7) asks “Why is water wet?”

Thanks team. Let us start with a investigation. Let us look at the way water interacts with different materials.

 

Let us now look at the properties of water drops. Firstly let me define ‘cohesion’ and ‘adhesion’. The term ‘hesion’ means  … to stick. Cohesion is is the attraction and sticking together of the same things while adhesion is the attraction and sticking together of different things.

Look at the image of the water drop below. Each water particle is attracted to the other water particles around it , this is cohesion. Now add a different surface and the water particles are attracted to that rather than each other, this is adhesion. When adhesion occurs we get the spreading of the water drop and wetting,  providing the adhesive forces are greater than the cohesive forces.

So what about your investigation? Is there any evidence of cohesion or adhesion?

Here is a thought. it has been suggested that water is ‘wet’ because you can feel it’s wetness.

Maybe another little experiment.

You could let me know by clicking on the ‘Reply’ box below.

“How does a magnet become a magnet?” asks Ava (11)

A brilliant question Ava. I asked my team for their thoughts.

Yes team you are quite right there are some limitations to magnet making. The main one is that only certain metals can be made into magnets. These metals are called ferromagnetic metals.

Included in this group are the metal iron and the alloys of iron with the metals cobalt, nickel and some other rare earth elements .

It is thought that in these metals (including iron) have some electrons called ‘free electrons’ (not sure what an electron is, then go to Science Master Special – Atoms and Atomic Structure). It is these ‘free electrons’ that are involved in magnetism. In the alloys the  ‘free’ electrons align themselves with the magnetism of the external magnet, making a (for the alloys) a permanent magnet. For iron alone the magnetism is only temporary and you can test this in the experiment below.

 

Look at the short video I have made below. In the ferromagnetic metal (iron alloy) crystal domains you will see free electrons. In the metal these will be moving freely. As they begin to interact with the external magnetic field, they begin to align themselves, making a permanent magnet.

 

 

 

 

 

 

 

 

 

 

 

Pete (10) asks “What is the pitch of a sound?”

Thank you team.  Lets first look at the motion of the particles. You suggest that the motion of the particles is in the form of waves. I think that is quite difficult to imagine but I think I have an example that will help illustrate this type of motion. Look at what happens when you drop a pebble in a pond. The pebble, when it hits the water, it creates  one vibration.

 

 

 

In this image the sound is produced by the piston creating the waves. Notice the wavelength, that is important. If we can manipulate the piston, make it go slower or faster  we can change the wavelength. Changing the wavelength is changing the pitch, think about that.  How does the sound change?

Try blowing over, or tapping, some bottles.

 

Pitch and Frequency ..Test your hearing a little bit more …….

In the video below you can see and hear how the pitch of the sound and the wavelength change together.  We measure wavelength in units called Hertz. 1 Hertz is one cycle per second. In the image above imagine that it takes one second to get from the flute to the ear. Then there are 8 cycles in the top sound is so frequency is 8 hertz and there are 3 cycles in the bottom sound so the  wavelength is 3 Hertz.

You can now test your hearing.    Take Care….make sure you have control of the volume.

 

 

Thanks to
Orion Lawlor, for the water ripples video, Published on 9 Jan 2011
Earmaster at https://www.earmaster.com/music-theory-online/
The ISVR from the Institute of Sound and Vibration Research, University of Southampton.
The Sound Video, unknown but thanks.

“How do people survive in the jungle?” asks Lachlan (8)

Thank you team, for your comments.

You are right Homo Sapiens survived because of their hunting and gathering skills.They were better at it than their fellow humans  Homo Neanderthal and the other human groups (Homo erectus, Homo ergaster, Homo rudolfensis …..)

Some clever people have found, that we still have hunting and gathering skills in our blood. So there you are, we will/might be able to cope in a jungle environment.

Revised 11/11/17 – added other homo species.

“Why does the sky go green when it hails?” asks Swifty (11)

What a question? Thanks  team for your thoughts. To me it seems to be a unique mixing of the colours from our sunlight. We know that the blue sky is because of the blue part of the spectrum of colour that comes from the white light from the Sun.

Some of the blue part of that spectrum of light is scattered when it hits the molecules of Oxygen and Nitrogen in Earth’s atmosphere. So blue coloured light illuminates the daytime sky. We know that when we see a sunset we can see a red sky in the distance and that is because we are looking at the Sun through a lot more atmosphere than we would do in a normal day. This is the dust that is in the atmosphere. In the experiment the milk acts as a ‘dust’ in the water.

I attach a NASA video that explains this then I will tell you my ideas about a green sky.

My thinking, and that of some others, is that the green sky is linked to the storm clouds (the background image above, was a pause in the hailstorm that the cyclists were experiencing). These were preventing some of the sunlight reaching the viewer who saw a yellow light mixed with the blue sunlight. the mixture of these lights could have caused the green light (a cyano type of light, like that below).

Very happy to hear comments and questions. Remember science development is about admitting your ignorance and my thoughts above are just thoughts. You and I need to do some further investigations.

Revised 10/1/18 to include experiment and colour example.

Keith (13) asked a question about thermal papers in cash machines.

Keith’s question
More and more places are using thermal paper as a form of receipt paper for customers. With time the information fades. How can one scientifically go about recovering information which may have faded from thermal paper.

Keith, many thanks for the question. I never realised that thermal(heat sensitive) paper was used in so many places and that it is also the basis on which the polaroid camera worked.

Thermal paper is made using a collection of dyes which exist as colourless crystals that become coloured when they interact with an acid.


For those who enjoy their chemistry you might have come across adding a dye called phenolphthalein to an acid solution. The dye changes from colourless to a deep purple.

The applied heat (from the cash register machine) melts a layer in the paper which contains acid crystals. The liquid acid then interacts with the layer below it which contains a colourless crystalline dye which changes colour as the acid interacts with it.  The print then shows. The acid quickly becomes crystalline again.

Over time the print does begin to disappear.

A little investigation.

Obtain an old till receipt which your adults do not want to save. Put it onto an ironing board and with a hot (care) iron, iron it.

Stop

To make it more scientific predict what you think might happen before you carry out the experiment. Any ideas, if so you have a hypothesis.  Now find a very old (fading) receipt and using a hair drier blow warm air onto the BACK of the receipt. Again predict.

I think I’ll stop there. Many thanks for the question Keith. Please comment or ask another question.

Braiden (9) asks “What makes a diamond so hard?.

Braiden, my question (before I turn you over to my team) is how do you detect ‘hardness’? Can you create an order of hardness with some common materials?
Lets say:

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 
For obvious reasons I have not included diamond in this list. I think that would be an interesting experiment to carry out. You will have to make sure it is a fair test 

Now over to my team.

Graphite has a layered structure with weak forces between the layers, This is a weaker structure than the close bonding of the diamond. The carbon atoms like the tetrahedral arrangement of the bonds with other carbon atoms. It is a very strong force.

Hope that makes some sense. If you have questions about the explanation please ask them. If you want to see my ‘hardness’ list go to Science Master Special-Hardness Results

Updated 15/1/2018  Experiment added.

“How did evolution happen?” asks Parm (10)

 

Parm, it’s all due to some wonderful stuff called DNA however the beginning of life is at the moment attributed to  a simpler chemical called RNA. Somehow 4.5 billion years ago, in a hot chemical quagmire a collection of complex chemical structure was formed which was living, it could reproduce itself. It is thought that this microscopic entity was quite close to the structure of present day bacterias although, it’s make up was completely different. For example it didn’t breathe Oxygen, it is thought that it might have breathed a chemical called Ammonia and it expelled Oxygen. It also, in its structure contained a crude DNA structure.

From this humble beginning all life on Earth evolved dictated by changes in the  DNA molecules that were part of their structure. Plants, Insects, Bacteria, Animals, Fungi, Algae,  all life contains their own DNA molecules which dictate their continued existence.

So for Jeremey, our snail there has been, for some reason, a small change in her/his DNA. The spiral is wrong. Maybe it might be wrong but it might help Jeremy eat a plant that he/she couldn’t eat before and therefore survive and breed more snails like him/her.

Over the millions of years that life has existed on our Earth, now and then, new life , created by old life, experiences a slight change in the DNA, and that means that the new life is slightly different from the life of its parents (plants, animals, fungi ….). If the new life survives, that life will create more new life in it’s form, evolution has taken place.

Hope this makes sense Parm. Any thoughts? Write them in the ‘Leave a Reply’ box.

Questions on electricity were asked by Gavin (10), Tegan (10) and Hayden (9)

Gavin asked “Why does the energy flow through the wires?”

Tegan asked “How does electricity work?”

Hayden asked “How do batteries springs and wires make a complete circuit?”

So how does this compare with a modern day battery. lets have a look and think about Gavins question.

Hayden and Tegan. In the circuit below the  energy flows around the circuit when the switch is closed. Why? What are wires made of? What is special? If the wires were plastic do you think electricity would be able to pass through it? Try and make your own circuits with different materials.

Electricity is linked to the passage of negatively charged electrons. These were very comfortable in the battery until it was connected to a circuit (a circuit is a continuous pathway) and the switch was closed. The circuit gave the electrons (negatively charged) a passage to the positively charged end of the battery. Electricity (electrons) flowed and accompanying the electrons was energy. Look at the Science Master Special on Energy and why not try the Circuit Quiz.

 

Do not play with mains electricity. It is very dangerous and could kill you.