“When the Sun blows up will Mercury smash into Earth?” asks Flynn and Freddie (10)

 

Below is a short video of the expansion of the Sun. Again this is a hypothesis based upon observations of our Universe.

The expansion is thought to be caused by firstly the Sun running out of fuel (it uses  Hydrogen, converting it by a fusion reaction to Helium). As the Sun cools the centre will expand, (any thoughts on what might cause this?) pushing out the rim of the Sun and consuming Mercury, Venus and The Earth and eventually it becomes a Red Dwarf. It is suggested that Mars will survive.

What is the difference between a hypothesis and a theory?

Hope this helped. Please comment or ask another question.

“If all living things were in one food chain, what would be at the top?” asks Chelsea and Ashli (10)

Thanks team. I found a nice little revision site on food chains that you might like to try, find it at Food Chain Game.

Now to your question. Firstly it might be a little difficult putting all living things into one food chain. Secondly do you think it would be humans?  Ecologists (They are scientists who specialise in studying the living environment) rank species by their diets using a metric*  called the trophic level scale. Plants, which produce their own food, are given a rank of 1. Herbivores, which eat only plants, are ranked 2. The fiercest of meat-loving predators, such as killer whales, are rated at 5.5. Humans are rated at 2.5 which is the same level as a pig.

If you want to make a comment please use the box below or you could ask another question.

* metric as a noun means a standard scale of measurement so you could call a temperature scale a metric or any other standard scale of measurement a metric.

(updated 13/9/17 -changed metric to measurement)
(updated 15/9/17 – ‘measurement’ back to ‘metric’ after realising it was the correct word in the context in which it was presented, added addendum explaining it’s use as a noun)

“What was the first plant that ever grew on Earth?” asks Mahdiyat (8)

So what now? Thanks team, some good answers.

It would be great if we could do some small investigations using Moss.

1.Firstly let us confirm that the moss has no stems or flowers.

2. Secondly a more long term experiment. Try ‘planting’ your moss on a rock. Before planting look closely at the surface of the rock. compare the surface 6 months after planting (and not disturbing the Moss).

Now a story ……..

The moss was the Earth’s first plant and it took over the world. It damaged the rocks it settled on and it took all of the Carbon Dioxide out of the atmosphere. This made the Earth very very cold (the first ice age). The coldness killed most of the moss and as the Carbon Dioxide built up again it allowed other plants to share the Earth with it.

 

How does the wind manage to topple things like wheely bins over? With the bins being big objects how is this possible? asks Imran (10)

 

A useful place to start Imran would be to look at the way in which wind is can exert a very strong force. Wind is created by the Sun warming up the ground around us and the air. Sorry team, I don’t think the wind does much pulling.

Air is made up of tiny molecules. When molecules are heated, they move faster. As they move faster they become become spaced farther apart, which makes the air less dense (meaning that there are fewer molecules in a given volume). This also means that the air has a lower overall pressure (pressure is the push of the gas on it’s surroundings. In comparison, cold air is made of more tightly packed molecules, and so it is denser and has relatively higher pressure.

The warmer, lower pressure air begins to move upwards and therefore it creates space below it which is filled by the colder higher pressure air. A wind is created. The hotter the air near the surface of the Earth the lower the pressure and the faster the rise. The 2017 hurricanes were caused by the hot sea and hot temperatures near the surface.

Can you measure how much push (force) is needed to push over a wheely bin?  Let’s first make our own push-pull measurer. You will need an elastic band, cotton reel, a couple of drawing pins, some sellotape and a paper clip to make your own measurer.

You can use it directly to measure pushes and pulls just by seeing how far the cotton reel moves up the dowel rod. It would however be better if we calibrated the rod in some way. In the images below the rod has been calibrated in Newtons (theses are the units of force). To do this a 500 gramme mass was attached to the hook. It is known that a 500g mass will exert a force (pull) of 1/2 Newton. So when the mass is attached, the elastic band will stretch, and the dowel rod will be pulled down. The distance on the rod between the ‘no’ force point and the 500g point is therefore equivalent to half a Newton.

It is estimated that an 80 mph wind would have a push of about 400 Newtons per square metre and be able to move a car. A breeze 5 mph might have a push of between 5-10N per square metre. You could try your meter on a sheet of cardboard in a strong breeze and see what you get.

Imran your question was very interesting to answer and you might have some difficulty in understanding some of the stuff above. If that is the case and also for anybody else reading this PLEASE ask another question or make a Comment.

“Why does my banana skin go brown when I peel it off? asked Gina (10)

Gina, it seems to be something about the ‘breaking’ of the skin of the fruit, which lets  in oxygen and allows it to react with some of the fruits chemicals.

We could test that idea. One way to test it might be to try and stop the ‘breaking’ of the skin of the banana. Can you think of a way of removing the skin without breaking or damaging it?

We could also test the role of oxygen. Any ideas how? If you have an idea why not try it  by comparing the speed of ‘browning’ for your oxygen and ‘no oxygen’ banana skin?

Remember to try and make the tests as fair as possible. Think about what that may mean. Remember a fair test means only changing one thing at a time while you try and keep all other things constant.

Let me know how you got on by Leaving a Reply in the box below.

“How are sounds made?” asks Mohammed (7)

Thank you team. Some of the things in the image above make sounds without tapping or blowing. Can you find them? Miwah asked a similiar question where he investigated how the sound a drum made was created. Can you try an make a sound using a ruler. Try holding one end of it on the desk and then bending it slightly by pushing down on the end which is not resting on the desk.

Now let go ….. and here come the questions.  Did you hear anything? What did the end of the ruler do? If there was a sound when did it stop?

Another question. If there was a sound what part of your body detected it? So how did the sound get to you? What is between your bodies sound detection and the ruler?

Now for a little bit of information. How did the ruler move when you let go of it? The word to describe this movement is ‘vibration’. A vibration is a continuous small movement up and down, or side to side. This is what Miwah discovered in the drum investigation. Below is a small video of a plastic ruler being pushed downwards and then allowed to vibrate.

Investigate making other objects making sounds and see if you can ‘feel’ the vibrations.

Any more thoughts , then please make a comment or ask another question.

Preethikha (13) asked a question about planting corn seeds in clay.

Preethikha you asked your question on behalf of your friend  Johan who appeared to be having trouble in growing his corn seeds in clay. I asked my friends about this and these were the ideas that they arrived at. 

The roots of the corn plant are very complex like most plants and they NEED oxygen . Clay is an important soil, it is full of nutrients which are important in providing the growing plant with food , HOWEVER  it is very different from most of the soils that we meet in our gardens.

Soils are composed of three types of particles: sand, silt, and clay.

The size of the particles varies, with clay having the smallest size and sand the largest.Smaller sized particles pack more closely together and slow the flow of water through the soil.The composition of a soil can affect the permeability (flow) of water through it.

There is the possibility that your friends corn seeds produce roots which are then ‘drowned’ in the surrounding clay soil. Investigate your friends soil and compare it to other soils in your neighbourhood. My next question for you is how would you go about investigating it ?

 

“I know I can see myself in a mirror but why cannot I see myself in other things?” asks Isabella (8)

Many thanks team. I have some ideas about investigations that you could do at home. People say that light travels in straight lines. How can we test this idea. Firstly we need a source of light. How about a torch. 

Now we know that a torch sends out light in all directions but how do we know if it is travelling in a straight line? Think……..

Now lets ‘capture a little bit of the light from the torch. Let’s use a piece of card with a hole in it and see if we can make the light from the torch go through the hole.

Now what do we have to do to show that, the little beam of light coming through the hole is travelling in a straight line?
Supposing we had another piece of card with a hole in it in exactly the same spot do you think you could arrange it so that the little beam of light goes through the hole in the new piece of card?

Do the same for a third piece of card arranging it so the little beam goes through it’s hole. Now draw a line between the torch and the third hole. What do you notice?

Now lets quickly look at your question about not seeing reflections in materials that are not mirrors.

Reflections are wonderful things and they happen, or do not happen because light travels in straight lines. A reflection occurs when a beam of light bounces off a surface. You could set up your torch and card above to make a reflection, using a mirror or something flat and shiny.

Now do the same for a different type of surface.try it with a piece of material. What happens? Try with all sorts of flat surfaces – shiny metal (use flat aluminum foil and then crinkle it), cardboard, paper, plastic, water, leather……..
What do you notice? Maybe reflection requires a flat shiny surface? Think about the results.

“How do you measure the distance to the Sun and stars?’ asked Julian (12)

 

Julian, quite a challenging question. I will only be trying to answer the first part – the Sun-Earth distance and the Earth-Stars distance.? Even then as my team suggests, I might be introducing mathematical terms that you have not met yet, but I have included links to other sources of help.

To answer the first question I recommend you read a Universe Today article   It is an excellent historical review of the problems that the early scientists had in determining the Earth-Sun distance. The answer finally came from observations of the movement of the planet Venus across the face of the Sun. In it the writer refers to a Nasa document that tries to explain the methods used. In present times the distance to the Sun is measured by ‘bouncing’ a radar pulse of of it.

Determining the distance to the other stars becomes possible once the Earth-Sun distance was known. It uses a technique called parallax.  I would like to illustrate this with a question which tackles a simpler problem. ‘How far is my finger away from my nose?’

Try this little experiment, put a finger in an upright position in front of your nose. Now close one eye and note the position of the finger. Close that eye and open the other one. The finger moves! Now suppose, with help, you could measure the amount of movement. You could end up with diagrams like those below. Did you make a note of the position of your finger relative to your nose? No – you can now see how you could work this out.

Now let’s do a little geometry and add an axis

We can then measure the angle of the apparent movement

You end with a right angled triangle ABC, knowing the angle x AND the distance between your eyes you should be able to do a bit of trigonometry using TAN x = opposite/adjacent (Tan x = AB/BC) and work out the distance of your finger from your face. For an introduction to trigonometry please look at this site.

Amazingly this is (in a crude way) the same process by which astronomers can measure the distance to the stars. Instead of using the distance between your eyes they use the orbit of the Earth. They look at a star and make a note of it’s position and then do the same thing 6 months later when the Earth is at the opposite side of the Sun. They therefore have AB (the distance between the Sun and the Earth and they have the angle through which the star has apparently moved. 

This gives the route to determining the distance between the Earth and a Star.

 

(revised 14/05/17)

 

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.