“What is the difference between speed and velocity” asks Sayed(11)

Absolutely right my friends. The two cars have the same speed but they are going in the opposite direction so their velocities are different.

An interesting example of the difference between
speed and velocity is when you look at an object moving at a certain speed in a circle. The speed is constant BUT the velocity is constantly changing as the object moves around the circle, see V1 and V2. The velocity at 1 is drawn as a line (representing the speed) pointing in the direction V1. This is a ‘vector’.

Sayed – this site is mainly directed at 8-13 yr olds so the answer above is very ‘general’. I have published it because younger readers might be interested in the difference between the two terms …for more information visit this site.

 

 

 

“Why doesn’t America use the metric system?” was Dekekisha’s (11) question.

Dekekisha, what a question.  Something that I have always asked myself when I have been converting Centigrade readings to Fahrenheit so that I could understand the weather. Friends, help me.

It is one of those occasions when I agree with you. As long as we all know and understand the different measurement systems and can confidently convert one to another.

Disagree, then let me know by clicking on the Reply button below. Thank you team.

Marcus(11) asks – ‘How do tsunamis form?’

tsunami

They seem to have left me to finish off.

You could try to create your own Tsunami. In a tank of water drop a pebble and look at the small waves that are created. Then (in an area where water on the floor is not a problem), drop a brick into the tank and look at what that creates. This movement of water becomes larger when the wave reaches the shallow areas (beaches) of the surrounding area. It gets bigger, faster and more powerful. Look at the excellent video below.

Sheereen asks – “Where do the items that a black hole suck up, go to?”

Sheereen, I was always told that a Black Hole was a place where my money or lost items apparently disappeared without trace. But I think your question deserves a different answer. I asked my friends about it. I shall also ask them to avoid science fiction stories where Black Holes seem to be used in a variety of stories. Do Black Holes really exist I might ask?

blackhole

My friends are right. The denser (more compact) the mass (think about mass and weight) of an object the greater its gravitational pull. So when the Sun collapses into itself you have a object that gets very small and very, very dense so it’s gravitational pull increases and it begins to pull everything in towards it. when something is pulled into it (including light) where it goes to is a mystery. It may add to the mass of the collapsed Sun and make a stronger black hole by increasing the gravitational pull. OR as the Science Fiction writers would suggest it takes you to a new dimension. Thank you for your question Sheereen.

Rainie (8) – asked “How do touchscreens work on phones?”

Rainie – what a question!  I thought I would start by presenting my team with the question….

touch

Rainie it’s all about electricity. Think about the ‘stuff’ that comes from batteries that makes your watch work or makes a torch light up the world. Electricity travels from place to place by travelling through things that allow it to travel through. It cannot travel through paper, plastics, stones and other things. It can however travel through water, some special glass, metals and you.

When you touch the screen of your telephone, you are allowing a very small amount of electricity to travel from the glass to you. The phone recognises this and knows where you have touched the screen. It then responds to the touch.

An experiment – touch the screen using a variety of materials on your finger. Try a damp finger, a finger covered by cloth, paper, aluminium foil, plastic and maybe a leaf. I am sure you can think of other materials. This little experiment might lead to other questions so please ask them.

Remember Rainie do not under any circumstances play or experiment with mains electricity. It could hurt you badly.

Ash asks “Why do we need academic learning, what is it’s purpose?’

Ash. This is a question I will try to answer without the help of my friends. It was a challenging question. This is a personal view.

I have tried to attempt academic learning for most of my life. Notice the word tried. Academic learning for me is learning things that would help me solve scientific questions. I learnt about materials and then about atoms and molecules and their properties and then about ideas on how this dictated the way in which they behaved. I then used this to help with my own ideas.

There are however lots of different forms of academic learning in all subject areas. Think of the people who are interested in history. Their learning could involve studying and interpreting lots of old and ancient texts – or modern ones. Does history help us in understanding what is happening in the world today?

Think of the engineer who would like to improve the jet engine. Look at the learning that she/he would have to do to help them solve the problems that jet engines might have.

Don’t however, in your life, avoid the other types of learning. Learning by listening, learning visually, and learning through actions are just as important.

Now and again academic learning involves tests, class test, school tests, national examination tests. They are horrible but on the other hand they help you in the steps of the academic learning that you go through.

Fatemeh asked a question about springs – in vacuum cleaners

Fatemeh asked the following question – “When you want to use a vacuum cleaner, you pull the wire out until you got the length you needed. The the length of the wire gets fixed. Then, when you want to rolls up the wire, you pull it out a bit and then you release it,it rolls up with the power of hands only.”

Fatemeh, I think this is a question about springs. To give me time to think I passed the question to my friends.

springs

Many thanks team.

Fatemeh. I suspect the vacuum cleaner observation is linked to springs. When you pull the power lead  out you are likely to be extending a spring. Your energy which you apply to pulling the power lead is being stored by the spring. When you stop pulling a device within the vacuum cleaner is applied to stop the spring from unwinding and losing it’s stored energy (the proper scientific term is stored potential energy)  …….until you give another little tug which releases the device and the stored energy is then used to pull the lead back into the vacuum cleaner.

To experience the way in which a spring can store energy try making one yourself from a paperclip. Get a big paperclip and try to wind it around a pencil.

paperclip-spring