Elizabeth (9) asked “How doesn’t stainless steel stain?”

Elizabeth I would like you try an experiment. Gather together some different nails. If you can, find a stainless steel nail, steel nail, iron nail and as many different nails that you can. Try and get two of each. Find two jam jars and put one set of clean nails in one jar and the other set of clean nails into the other jar. Why do I suggest cleaning the nails?

Fill the first jar with tap water and the second with water that has been boiled and cooled. Cover both with cling film and leave for about 7 days. What happens ?????

Relook at what you did at the start. What did  you see in the tap water that you added? How did this compare to the boiled water? What did you see when you boiled the water?

Most of the stains on metals are caused by interactions with water and oxygen.

When steel and iron are attacked on their surface by the oxygen from the water you get  things called oxides created as the oxygen (a very reactive gas) reacts with the metals surface. For most metals the compound (oxide) that is formed is fairly ‘soft’ and is washed away creating new sites for oxygen attack. With stainless steel it is the chromium in the stainless steel that reacts with the oxygen creating an invisible layer of Chromium Oxide and this is such a hard substance that no other substance can stain the steel.

If you rub the stainless steel implement hard with a scraper you might get rid of the strong oxide and create a stain by attacking the surface of the steel with another substance. Try it (with permission).

Elizabeth and others, quite a detailed answer. If you want to ask further questions please ask.

Elizabeth (9) asked “If you picked up a shell from the beach and put it close to your ear why does it have the sound of waves?”

 

Elizabeth, I think we need to do some experiments, firstly did you know that sound can be reflected? Sound can be reflected like light, and like light the surface it bounces off can affect the bounce. Try reflecting sound using a mirror (preferably plastic). You could use a loud ticking clock as a sound source. You then use your ears to detect the reflection. Now cover the mirror with some paper see how it affects the reflection. You might have some difficulty in making the experiment ‘fair’ but never mind (a sound detector would help make it fairer).

Now instead of a shell, place (carefully) a cup over your ear and listen. Replace the cup with a closed cardboard tube and listen. Do you hear anything? You might hear a low quiet whistling sound. Try making the tube shorter/longer and see how it affects the sound.

How was what you heard different from what you heard when you used the shell? What is the difference between the surface of the cup and cardboard tube and the shell surface?

My thoughts are that we are living in a ‘sound’ environment. Putting the cup over our ear cuts out most of the sound but not all of it. We call that an ambient sound. This sound manages to enter our cup and it is bounced around in the cup, but inside a shell the bouncing is slightly different.

Let me know what you think by filling in the Reply box below and post your comment or ask another Question . Anybody can do this.

Mattheiu (Yr 4) asked “If sound can’t travel through vacuums, why are they so loud?”

 

This is an excellent question. We are told that sound travels through the air to us by the vibrations of the air molecules between speaker and listener. But how does is get to us from a very distant speaker? Or through a vacuum? The magic formula is that one form of energy can be converted to another form of energy, as my team have explained.

If we can convert one form of energy to another then why not convert sound, which is moving air and therefore kinetic energy (the energy of movement) to electrical energy that can be passed down a wire or through a vacuum as an electromagnetic wave to a listener a long way away. When it is received the reverse conversion process can take place where the electrical energy can be converted back to kinetic energy, via electromagnetics and loudspeakers and not forget ears and brain.  Then by controlling the input to the conversion process we can control the loudness. Magic but real.

See my Science Master Special on Energy

Any reader can ask another question or leave a Comment in the Leave a Reply box below

Elizabeth (9) asks “How does sand form in a desert?”

I agree we need to do an investigation.  The suggestion is that the desert sand might have come from the soil. Let’s see if we can find sand in the soil around us. Before we do this lets think about soil, the soil in your garden. What do you think it is made of? Maybe it is just made of soil? Maybe it is made of a mixture of things? Let’s investigate these questions.

Collect some soil. Get a plastic transparent beaker or a jar with a lid. Put a couple of small spoonfuls of your soil into the container. Add enough water so that it is half full. Cover and shake for about 20 seconds. Put it down and wait for about fifteen minutes. Now look at it and make notes on what you see. Repeat with another sample and another beaker or container (investigations always need to be checked).

Has your experiment resulted in layers of stuff in the beaker? Maybe a bit like the layers in the image below.

If it has then think about why you have layers? What has formed the first layer and why? Was it because it was the lightest or heaviest ‘stuff ‘ in the jar (soil)? Is the second layer made up of ‘stuff’ that is lighter or heavier?

The bottom layer is ‘sand’ …..the heaviest ‘stuff’ that makes up soil. The other layers are ‘silt’ and ‘clay’. Look at the diagram that my friends have given you the sand particles are the biggest.

Now to deserts. In very arid (dry) conditions the soil dries out. The wind basically blows away the smallest particles of clay and silt leaving the largest so a desert of sand is formed.

Elizabeth … thank you for your question.

“Will we ever discover aliens?” asks Frank (9)

Frank, as my team suggested, in 2009 NASA’s Kepler telescope began pointing at a small patch of sky for four years. In that time it found a series of stars with Earth like planets surrounding them. If you multiply this little bit of the sky to cover the whole Universe you are talking about over 50 billion Earth like planets. A good assumption would be that some form of life found it’s way to existence on some of them. Maybe they have yet to develop, like us, a way of communicating over the great distances involved.

If you are a teacher read the following Guardian article Updated 26/02/2017

Shabaar (9) asked “Can humans cause an ice age?”

The last ice age ended about 11,700 years ago. It started almost 3 million years before that and was thought to have been caused by changes in the way that the Earth moved around the Sun.

So can we cause a new ice age? From this evidence it seems unlikely that we (humans) can cause a future ice age. With our production of greenhouse gases (Carbon Dioxide, Carbon Fluoride compounds and other related gases) it likely that we will be warming the atmosphere rather than making it colder. This may cause weather extremes which might make life on our planet (for humans) unacceptable. See the following link

Jamie asked a question – “Why does water sometimes boil at different temperatures?”

I must apoligise to Jamie because he specifically asked about the water in Yellowstone River boiling at 106 0 C.  Why does it do that? Does water boil at a higher or lower temperature in other situations? I asked my friends about this.

Jamie, the properties of water does depend on it’s intermolecular structure. If it didn’t have these intermolecular forces (called hydrogen bonds) the water would likely be a gas at room temperature. Life on Earth would therefore be impossible or maybe very different.

Ok, water is as it is now, so why can it’s boiling point change? The main reason is the environment in which it is trying to boil, not the water. Boiling is linked to the process of the water molecules getting enough energy from the heat source to make it move so fast that the intermolecular forces can be broken and it can escape from the water into it’s environment.

BUT

If the environment is changed this can affect the boiling point. Make the environment thicker(more dense) and the water molecules have greater difficulty in escaping making the boiling point go up, in the kitchen a pressure cooker prevents the faster water molecules from escaping.  Make the environment thinner (go up a mountain, where the air is ‘thinner’) and you make it easier for the water molecules to escape so the boiling point goes down.

HOWEVER

There is another way to affect the intermolecular forces of the water molecules. Introduce something into the water that increases the intermolecular bonding. Introducing salt NaCl, which gives Na+ and Cl ions in water. These make it more difficult for the water molecules to become gaseous molecules so the boiling point go up.

There are other posts that could help you…..On intermolecular forces and a game you could play and adapt.

Poonie (9) asked – “Why do cats always land on their feet?”

Poonie, many thanks for your question. Having been a cat owner for the last 20 years I have always been interested in this BUT decided that I did not want to experiment on my 19 year old cat (Marley). I think  I will rely upon other people’s experiments to try and answer your question.

Apparently it’s all to do with, muscular reaction. Somehow they can rotate their body very quickly, within seconds of beginning a fall. I’ll talk my friends about it, and asked if any other animals can do this.

This little video, made using a flicker book, illustrates how the cat changes it’s bodies position as it falls

One of my friends suggested that you should look at cats and the positions that they take in their everyday life so that you can understand how flexible the backbone/spine of a cat is. Record what you see and let us know. Can you position yourself in the same way as a cat does? Possibly in some positions, but what about the other positions?

‘How many volcanoes can go off at once’ is Charlotte’s (9) question

Charlotte it might be worth reminding ourselves of what is a volcano, and why do they occur. I’ll let my friends start the discussion.

volcanoes

Some interesting thoughts team but we have to look at Charlotte’s question.’How many volcanoes can go of at once?’ Firstly there are recorded to be 1500 volcanoes in the world as we know it. There are also lots of volcanoes under the sea but we don’t know how many. Of the 1500 about 500 have been active over the last 100 years. So Charlotte,  it is quite difficult to give you a definitive answer. For a volcano to erupt there needs to be some activity in the magma (the molten core of our Earth) and maybe the tectonic plates (the mantel plates that make up the surface of our Earth). Where the plates meet there is lots of tension, this normally causes earthquakes (New Zealand) but could allow magma to escape via a volcano.

Elizabeth (9) asked a question on lightning

Elizabeth, thank you for your question. “How many %C is the air surrounded by lightning?” I am sorry that I had a difficulty in understanding it. Are you asking about the temperature (degrees C) or are you asking about the Carbon (C) in the air ?  As it was a question about lightning I thought I could ask my friends to talk about that. If you want to revise your question you can easily ask it again. lightning-strike

Thanks team, some very interesting observations.

What I find interesting is how does lightning happen. It’s all about clouds. Hot weather produces lots of evaporation of water from our oceans. The hot air and water mixture rises, look at the clouds from a kettle. As it rises, the cloud of water vapour and air gets colder, and colder. The water turns into very small ice crystals which are still lifted by the cloud of air that they are in. As this happens it is thought that the ice particles separate ……. the lighter particles move to the top of the cloud while the heavier particles remain at the bottom.

The water/ice particles have a small electrical charge associated with them. When they separate the charge moves with them. It is likely that this causes an uneven redistribution of the total electrical charge. If you have more lighter water/ice particles at the top of the cloud than heavier ones at the bottom the difference in the total charges could be significant. So ‘flash’ they try to equalise and thus the lightning flash. It’s the process of the ice crystals at the top of the cloud trying to get rid of their excess electrical charge by giving it to the heavier ice crystals at the bottom of the cloud.

Sometimes difference in charge is so great that the ‘flash’ continues to the ground, but if you are in a storm and look at the flashes a lot of them are within the clouds themselves.

Elizabeth, sorry for such a long explanation. It was such an interesting question. If you have any other questions linked to what my friends and i have said please ask them.

Elizabeth. Some additional information ……. Look at this site. The type of electricity that is built up in clouds , before the lightning flash is static electricity. There are some experiments you could try.

(added 20/11/16