“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.

 

“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.

“When you shake a fizzy drink that is full when you open it and it explodes?” asked Ruby (8)

When you open the bottle you should hear a gentle fizz. When you pour the drink into a glass you get a bigger fizz and lots of bubbles. If you had ice in the glass you would get even more bubbles. This is because the surface of the glass and the ice cubes are full of little gullies and points. The gas bubbles that were hidden in the liquid attach themselves to the gullies and start to get bigger, (bubbles grow by being joined by other bubbles) and bigger and then when they are big enough, because they are lighter than the liquid, they rise to the surface.

Here is a little experiment for you to try —put the ice cube in your mouth and get your tongue to smooth it, for a few minutes. Think about what I have said and try and predict what the outcome will be when you pour a new bottle of drink over it. Now add the carbonated drink and test your prediction.

Now what happens if you shake the bottle before opening it. This is where you get the explosion!  Here is my possible explanation……. look at the bottle of drink.

(1) There is an empty space at the top of the bottle. It’s not empty, it is full of Carbon Dioxide gas.

(2) When you shake the bottle that gas mixes with the liquid and because bubbles attract other bubbles the gas in the liquid becomes more bubbly.

(3) The bubbles that were hidden in the liquid join the new shaken bubbles. Undo the top and these new bigger bubbles all escape at the same time pushing the liquid before it – the  explosion.

Look at this previous post.

 

Ruby (8) asked “What type of chemical is in capsicum that hurts when police put it in eyes?”

Yes, a great question Ruby. There is this temptation to relate Capsaicin to Black Pepper, however this is not true. The black pepper seeds are from a plant in the vine family of plants. The Capsicum family is the home of the chillies and the chemical Capsaicin which is a chemical in the alkaloid family. Capsaicin is not only used in pepper sprays it also has some curative properties, for example it is an effective pain killer.

I think it is very interesting that certain chemicals, particularly those derived from plants can be used for destructive purposes and for curing purposes. Just a thought.

Sadie (8) asked “How do touch screens like iPods work?”

Sadie, I and my team  have already answered this question. See this answer to Rainnie.

To check on whether a question has already been asked go to the right hand column there is a SEARCH THE SITE  box. Type a keyword , like ‘Touch’ into the box and then click enter on your computer. It will lead you to the answer I have connected you to .

Sadie, thanks for the question. It shows how important it is to Search First.

If  you are uncertain about some bits of the answer then please feel free to Ask Another question.

“When your car crashes why does a fire start?” asks Ruby (8)

Ruby, I hope this answers your question. If you have some other thoughts you can make them in the Leave a Reply box below or ask another question.

 

Sadie (8) asked “How do batteries work?”

Sadie, many thanks for your question. I asked my friends to help me…

 

Yes I remember doing that, it wasn’t easy but I did get the led to light up.

Let’s start with a possible definition of a battery – It’s a device that converts chemical energy into electrical energy. If you are uncertain about what I mean by energy then have a look at this site.  

Now why do we have two different metals? Inside the squeezed lemon is a lot of lemon juice. There is a chemical reaction between the metals and the lemon juice. Because the metals are different they react with the lemon juice in different ways. The different reactions give the copper nail a positive charge and the iron nail a negative charge.

Connecting the two nails together with a wire will give you a flow of electrons in the wire from the iron nail to the copper nail. This will continue until the chemical reaction inside the lemon reaches completion.

Your normal battery is like the lemon but obviously made of different materials. Look at the diagram below.

Sadie, I hope you have found this useful. If you or any other reader would like to make a comment please fill in the Leave a Reply box below. And if you are uncertain about bits of the explanation please ask another question.

Additional note …copper nails are difficult to get hold of so why not use a small piece of copper tubing. Also there is a small possibility that a battery was produced over 2500 years ago, see The Baghdad Battery. Ask your teacher about it. Or ask another question.

“Why does a coke can explode when a mentos goes in. Is it a chemical reaction or just fizziness?” asks Bella (8)

Some good observations . The bumpy surface is the real reason for the fantastic reaction between the coke and the mentos.

Think about the coke. It is a fizzy drink. How has it become fizzy? In the making process a lot of gas (Carbon Dioxide) is dissolved in the coke under high pressure . Water has lots of air dissolved in it. There are quite a few liquids that can absorb gases.

So what happens when the mentos is dropped into the coke? It’s all to do with surface. If the mentos had a completely smooth surface, like the inside of the coke bottle very little would happen (you can test this). However look at the image above, the mentos tablet is covered with valleys and holes. Each of these sharp points is a place where a bubble of the gas absorbed in the coke can attach itself to and therefore remove itself from the coke liquid. 

The gas bubble is lighter than the liquid coke, so what does it do? It moves upwards (it’s lighter than the liquid so it floats). Millions of bubbles begin to move upwards. What is in their way? Coke liquid.

There are lots of things to investigate here. Start doing some science. Do shiny things create bubbles? Do the number of mentos tablets increase the explosive effect? How can you measure it fairly? Does the temperature of the coke affect what occurs.

Have fun but test the ideas that I have presented you with. Science can be fun. If you want to ask another question, do it. If you or any other reader would like to make a comment use the ‘Leave a Reply’ box below.

Sorry I forgot one of your original questions. The bubble forming and bubble emission processes are physical and not chemical processes.

 

“Why do metals always feel cold when I touch them?” asks Chen (8)

My question is, are the metals colder or warmer than the things around them? We need to test this question. So how?

We need find out if other materials behave in the same way.  We therefore need to test it with other materials, for example, wood, plastic, china and glass.

To make the test fair (an important part of my experiment) we need to make sure that all of the materials are at the same temperature at the start of the experiment. We can test this by taping a thermometer to the materials, leaving it there for a period of time (maybe 5 minutes) before touching each of them. Do they feel hot or cold? Do they feel like they are at the same temperature that you are.

What did you find out? If the metal, or other material did feel colder, or warmer, than the others then why?  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.

Ethan (8) asked “How can you hear things?”

 

Ethan. There are some other small experiments I would like you to try.

Find a ticking clock and a box that you can put it in.  Listen to the ticking with the lid on and the lid off. could you hear the ticking when the lid was on?  Now with the lid on get a cardboard tube (maybe one from a tube of kitchen roll) , put one end of the tube on the box lid and the other end over your ear. Listen. Is the sound of the ticking louder when you use the tube? Move your ear away from the tube. What happens to the ticking?

Ethan, lots of questions from me to you.  Maybe the experiments have created some more questions. Any reader can ask a question or leave a Comment in the Leave a Reply box below

Also see Clara’s question on sound.