Charlotte asks the question “How does gravity hold you to the ground?”

Charlotte I can honestly say that I have no idea how gravity holds things down. I have asked my friends and await an answer.

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Charlotte, my team seem to agree with me. In the 17th Century Newton and another scientist called Hooke did some great observations and experiments on falling objects and proposed that gravity was an attraction between any two masses AND the attraction was dependant on the size of the masses involved. For example you are attracted by the Earth and the Earth is attracted by you BUT your attraction is so much smaller than that of the Earth it does not affect the motion of the Earth. The attraction between you and the Earth is also dependant upon how far away you are from the Earth. The Moon is attracted by the Earth and the Earth is attracted by the Moon. They are both big bodies so gravity does affect the way they move with respect to each other and this dictates how the Moon orbits the Earth.

Some scientists including Einstein have put forward ideas on how gravity operates but even these are being challenged. There a lots of things which are still unanswered. The question just has to be asked.

Charlotte, the Earth’s circumference can be calculated by multiplying the diameter of the Earth by pi.(π)

Marcus (11) asks – “How does our brain control our body”

Marcus. Many thanks for your question. I must admit that I am happiest with questions relating to the physical world rather that the biological world. But like a good scientist I was curious so I asked my friends to tell me about how the brain might control the body. For once they came up with some answers.

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This is certainly interesting. for the brain and different parts of the body to contact each other they use nerves (bit like wires), they also use electricity – but a different type of electricity to what we usually meet The nerves use positively charged particles to send the messages, we in the real world, use negatively charged particles.

I found out that there are two types of circuits. Some are linked to things that the brain has put on automatic and some are linked to response/reply circuits. These are the autonomic nervous system and the others are the ones which your brain can control are called the somatic nervous system. Can you draw up a list of the autonomic  functions that you brain controls. How many items do you come up with. Want to let me know click on the Reply button below or leave another question. Thanks for the question.

Fizzy drinks – A question from Nicholas (11)

Nicholas asked a question about his fizzy drink – “When you open a can of fizzy pop, what keeps the bubbles in the liquid? Why does it go flat slowly and not all at once, as soon as you open the can?” I asked my friends about this.

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The experiment involved slowly warming a saucepan of water. Long before it boiled lots of bubbles appeared. These were not steam bubbles but bubbles of air and they were slowly coming out of the water. There were no bubbles before I started heating the water. So where were they? Where were they hidden in the water? You might not believe it, but in water and other liquids, there is quite a lot of space for the air to hide itself. Your fizzy drink had quite a lot of space to hide the gas particles that they put in fizzy drinks (carbon dioxide).

Let me tell you about how I devised an activity to explain how this space came about in solids, liquids and gases.

Imagine you are with a group of people and you are asked to imagine that each of you is a particle of a solid – let’s say ice. Because you are a solid you will not be moving (you might be vibrating slightly). You will probably be part of a lattice of non moving particles. They were non-moving because it was ‘cold’ and  they had been asked to put their hand on to a shoulder of the person next to them.  I then told them that things were getting hotter (getting hotter, means giving them more energy) and that the firm bonds were going to break BUT they still had to remain in some loose contact with each other. As it got hotter they were to move more quickly around the room but they still had to be touching somebody else all the time. It was just a touch, maybe one hand touching another, no holding and they could  move from person to person but always be in a situation where they were touching somebody. They were no longer a solid they were a liquid. I then asked them to STOP and look at the space they had created …..space for air bubbles, and fizzy drink bubbles, space for other solids to hide in. (revised 24/7/2016)

What do you think happens when things get even hotter and everyone  is moving a lot faster? What will the particles become?

Sorry for the long explanation. I hoped it helps in your own understanding.

Two questions on electrocution and why does my phone get warm?

…. a couple of interesting questions. Which I will answer.

Electrocution is the term used to describe death from an electric current.

If you are going to die from an electric current it has to have certain properties. The voltage (or push) of the current must be high enough and the amperage (strength of the current) must be high enough. The electric current must also travel through the body in such a way that it passes through the heart or brain because it is those two organs that are most easily damaged by electricity (they both operate using electrical signals produced by the body). Electricity also has to have a pathway to the ground so if your feet are covered with an insulating material it might burn you (at point of contact) but is unlikely to kill you. To electrocute you the voltage could be as low as 40 volts and the current 500mA. Remember a battery can only produce a push of 1.5 volts and provide a current of 2000mA so even though the current is high the push is very low.

Mains electricity has a push of 250volts  and can provide a current of 13,000mA so it is very, very dangerous. Never, never, play with mains electricity. 

Warm telephones are caused by your working battery. Your battery is pumping electricity around your phones circuits. That electricity is lighting up the screen, and converting your voice into electrical signals, and converting the electrical signals of the person you are talking to into sound energy and sending the signals. It’s doing a lot of work. You get hot when you are working and try to cool down, the battery gets hot and tries to loose that heat by warming up your phone.

I hope these comments answer your questions.

Abdur asked: I got lazer and pointed it in my tea.Then I looked up and I could see the reflection on the ceiling. Doesn’t only mirrors reflect things?

An interesting question Abdur. I asked my team to have a think about it and as usual they came up with more questions.

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I think we could investigate some of the statements that my team came up with. If it was very dark would you be able to see the tree?  Think about why you see things. Do you see the tree because it creates it’s own light? Maybe it is not only mirrors that reflect light? Abdur saw the laser beam on the ceiling when he was shining it at the surface of his cup of tea. Maybe the ceiling can reflect light? You look at your hand and you can see it. Is it producing it’s own light or is it reflecting light?

I think you need to do an experiment. If you have access to a light detector (some schools have them) look at the light reflected from different surfaces. Try a mirror, try a white surface, try a leaf, try a black surface and see how much light the different surfaces reflect. Some cameras also have light meters.

Mo (age 11) asked “Hi Science Master, how do people know metal is a good conductor and how did they find out it was a good conductor?”

Mo, I asked some of my friends about your question and they came up with some interesting thoughts of their own. Think about the comments and then look at my thoughts.

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What is the difference in electrical conductivity of two different metals? Maybe you could construct a simple circuit with a battery and a light bulb connected by copper wire. You could measure how bright the light bulb was by using a light detector (you may have them in your school). You will have to decide how you are going to use the light detector to measure the brightness.

Now get some aluminium foil which is the same as the weight of copper (fair test) and use the foil to connect the battery to the light bulb and again measure its brightness. The brighter the bulb the least resistance there is to electricity moving through the circuit and the better the conductor.

DO NOT EXPERIMENT WITH MAINS ELECTRICITY

Do you know the answer to the question? If you do click on the Reply button below. Want to ask a further question?