How many electrons are there in the average bowl of cereal?
November 9th, 2011 by Michael de Podesta
Well typically breakfast consists of around 200 grams of cereal and roughly 200 millilitres of milk. For these purposes I will make some assumptions:
First assume that the cereal is made up completely of carbon. 12 grams of carbon contains approximately 6.023 x 1023 atoms of carbon (The Avogadro Number from earlier on). So 200 grams of carbon contains (200/12) ~ 17 x 6.023 x 1023 atoms. Each atom of carbon contains 6 electrons. So the final total is 6 x 17 x 6.023 x 1023 which comes to 6.14 x 1025 atoms.
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What is science?
October 29th, 2011 by Michael de Podesta
The word Science is derived from the Latin word Scire – ‘to know’. It is probably related to the word ‘scindere’ (from which I think we get ‘scissors’) which means to split or separate – i.e. it means to sort things out.
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A carbon neutral gym?
September 5th, 2011 by Michael de Podesta
While sweating and struggling in a gym, you may have wondered if all the energy you’re putting into your workout could be put to some use. How about, using that energy to help power the lights, or the actual treadmill you’re running on, rather than it all being wasted. What’s more, could all this energy being produced actually offset all of the gym’s power needs and create an entirely carbon neutral gym?
Let’s look at the power 20 squad members in a Rugby team training together might produce.
- Rowing Machines: If I try hard I can generate 150 W of power on a rowing machine for around 10 minutes. Let’s assume rugby players can generate for 250 W for 15 minutes. If we had 5 machines then we could rotate banks of 5 players through these machines to generate a continuous 5 x 250 = 1250 W – that’s impressive .
- Treadmills: A treadmill actually consumes energy, and a typical device might have a 2 horse power (1500 W) motor. So either we could have 6 rowing machines powering one treadmill, or more sensibly, we could just abandon treadmills and get the team to run around a Rugby pitch.
- Exercise bikes: I don’t have a figure for bikes, but in my experience they are less knackering than rowing so I would guess they can generate less energy. Let’s guess we have 5 exercise bikes and each one can generate 150 W then we could rotate banks of 5 players through these machines to generate a continuous 5 x 150 = 750 W.
- Cross Trainers: I don’t have a figure for cross-trainers (sometimes called elliptical trainers), but in my experience they are less knackering than rowing but more knackering than exercise bikes, so I would guess they can generate power somewhere in between the previous two. Let’s guess we have 5 cross-trainers and each one can generate 200 W then we could rotate banks of 5 players through these machines to generate a continuous 5 x 200 = 1000 W.
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What is the purpose of yawning?
June 17th, 2011 by Linda Dinc
Yawning is an involuntary respiratory reflex, which regulates the carbon dioxide and oxygen levels in the blood.
A yawn is commonly triggered either by fatigue or boredom and when a person is tired or bored the breathing is not regulated and it is shallow, and little oxygen is carried to the lungs by the oxygen-toting cardiovascular system.
Yawning elevates ones alertness, as the sudden intake of oxygen increases the heart rate, rids the lungs and the bloodstream of the carbon dioxide buildup, and forces oxygen through blood vessels in the brain, while restoring normal breathing and ventilating the lungs.
Yawning is a kind of physiological mechanism that is designed to maintain attention and regulate our breathing.
Tags: Biology, yawn
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Fukushima: What happened?
April 19th, 2011 by Michael de Podesta
It’s been 6 weeks since the Fukushima nuclear accident, and news reports of the incident vary from the facile
to the mundanely exagerated
However, I have yet to read a clear web account of what has actually happened! The Wikipedia timeline somehow confuses rather than elucidates. A couple of weeks back I was lucky enough to receive a PowerPoint presentation by Mattias Braun from Areva. Using this and other sources I have attempted to summarise what actually happened.
The Fukushima Daiichi Site #1 consisted of 4 boiling water reactors:
- Unit 1 – GE Mark I BWR (439 MW), Operating since 1971
- Units 2-4 – GE Mark I BWR (760 MW), Operating since 1974
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Is there any genetic link between insects and plants, that could explain mimicry eg. Mantis orchid
January 25th, 2011 by Sven van Eijl
The first part of the question can be answered in the affirmative; yes, there is a genetic link between insects and plants. In fact, there are genetic links between all living things. This is one of the amazing facts modern biology has revealed to us.
Then the second part: can this link be an explanation for mimicry eg. Mantis orchid? This is almost surely not the case. To find out why, we need to have a look at the relations between all living things according to the theory of evolution.
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Why split the atom?
November 15th, 2010 by Michael de Podesta
First of all the phrase ‘splitting the atom’ is a misnomer – atoms are ‘split’ all the time as they lose electrons in chemical reactions. The phrase really refers to ‘splitting the nucleus of an atom’. You can read more about this on my answer to the question What does “splitting the atom” mean?
Normally the nucleus of atoms is ‘protected’ deep within the atom. But it is possible to split the nucleus by hitting it with (for example): a neutron; a very fast moving proton ; or a collection of two protons and two neutrons which is known as an ‘alpha particle’. When the nucleus is split, two new nuclei of two different atoms are formed.
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Why don’t tortoises die from starvation and thirst when they are hibernating?
November 1st, 2010 by Sven van Eijl
To answer this question we should first ask ourselves why they need to eat and drink in the first place. Any animal, also a tortoise, needs food to provide it with energy. It needs energy to power its muscles, and keep its body temperature constant in the face of changes in the enviromental temperature.
It needs water because its body (like any animal) is to a great extent made up of water. But there is a continuous loss of water through sweating and the production of urine. Sweating contributes to cooling of the body, and urine will excrete some of the waste that is produced when the animal extracts energy from its food.
Tags: Biology, hibernation, tortoises
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Why is ice clear and snow white?
September 2nd, 2010 by Peter Stotereau
Snow comprises huge numbers of ice crystals with lots of trapped air between them. If we could look at a single tiny ice crystal within the snow, it would look clear.
Visible light from the sun is made up of components of different wavelength (the electromagnetic spectrum as in a rainbow; red, orange, yellow, green, blue, indigo, violet). When the light hits a single ice crystal, some of it is absorbed and some reflected back; on passing through the crystal the light changes direction due to a process called refraction, as in a prism, and can be internally reflected within the crystal.
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How do 3D glasses work?
August 12th, 2010 by Michael de Podesta
Normal 3 D vision works because our left eye has a slightly different view of the world from our right eye.
3 D glasses typically have the left-hand optic covered in red and the right hand-optic covered in blue. The 3-D material – a picture or a single frame of a film – has two images printed, one in red and one in blue. When we view this image through the glasses our left eye mainly sees the image printed in red and our right eye mainly sees the image printed in blue. Our brain interprets the differences between the different images as being due to differences n perspective and reconstructs a 3-D view of the scene. Read the rest of this entry »
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