[NakedScientist (OP)]

Quantum - if you do want to discuss things related to QOTW then please feel free to start a new thread in a relevant section of the forum.

TNS

[NakedScientist (OP)]

I think the issue of why we have seasons has been explained better than we could have done, so no further comment from us needed...

Anyway here is this week's QOTW (Question of the Week) :

"WHAT HAPPENS IF YOU LIGHT A MATCH INSIDE A SPACESHIP WHILST IT IS IN SPACE ?"

Have a go, below. Please remember that we love questions to come from you guys, so please put forward suggestions for future questions via this email address : qotw@thenakedscientists.com

TNS

[Ians Daddy]

KABOOM!!!

[Quantumcat]

I remember learning about flames in low gravity, I can't remember completely. It looks like a demi sphere, and it's a different colour.

I have a theory of how flames work, but no one has ever told me the real way they work. Perhaps you guys can tell me. My theory is that the heat gives the atoms energy to leap off the wood, they emit light as they go then fall back to earth as ash. Different atoms jump different heights, atoms that emit blue light don't jump as high as atoms that emit yellow light (carbon right?) but they jump higher than green light-emitting atoms. Sparks are lumps of atoms who couldn't prise themselves apart but emit light all together all the same. Because they're larger they get to jump higher than other atoms of the same kind that aren't sparks, because the breeze catches them. Coals glow because the heat has constricted them, they are too big to be carried up by the breeze and the atoms can't jump off them, so the atoms just emit their light without moving. There is considerably less matter when the fire is done because a lot of it was changed by a chemical equation into heat (I learned that at school, didn't make it up lol) the ash is all the light-emitting atoms and the chunks of black stuff were the coals. If anyone knows how it really works I would like to know. Thanks.

Am I dead? Am I alive? I'm both!

[tweener]

Ronnie might be right if the spacecraft has pure oxygen for an atmosphere, but I think after Apollo 1 most people know better.

I believe that the flame would make a sphere (or close to it) around the head of the match.  It would keep increasing in radius while it burned, but it would not burn long.

This behavior is due to the lack of gravity causing there to be no density gradient in the air.  In a gravity field, the air is always more dense the lower you go.  When it is heated, or a hot gas is introduced, the hot gas is less dense than the surrounding air, and thus floats upward.  If there is no density gradient, then it does not float, it just stays put.  In the case of the match, the chemical reaction of burning is releasing hot gases from the wood, and thus the "flame" is going to keep increasing until the match burns out.  The match would stop burning quickly because there is no fresh air (oxygen) reaching it (it is surrounded by its own gases).


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John

[NakedScientist (OP)]

ANSWER TO LAST WEEK'S QUESTION OF THE WEEK "What happens if you light a match inside a spacecraft orbiting the earth ?"

This question concerned the early pioneers of space travel a great deal. But tests showed that flames just don't work in space - to understand why not you have to first consider what a flame actually comprises.

Flames always point upwards. That's because gravity creates a density gradient in the air so that hot air, which is less dense, rises whilst cold air sinks. This is why a hot-air balloon can float.

So when something burns the hot vapourised fuel (which is rising) pulls in cold fresh air from the bottom (containing oxygen) which oxidises the fuel and creates more flame and heat. The heated vapours rise and so the process continues.

But in space, under 'weightless' conditions, there is no density gradient in the air because there is no up or down ! This means that when you try to burn something, the vapours cannot rise away and so the fire suffocates itself because fresh air (oxygen) cannot gain access to the fuel sufficiently quickly.

So, unlike Ian's Daddy's suggestion "kaboom", the more likely outcome would be something like "phutt".

TNS

[NakedScientist (OP)]

HERE IS THIS WEEK'S Q-O-T-W :

"WHY DOES HELIUM MAKE YOUR VOICE SOUND FUNNY ?"

Have a go, below :

TNS

[cuso4]

This is a guess.

We make sound by making the air vibrate. Since helium is much lighter than air so when we speak, same amount of energy will make helium gas vibrate much more. Higher frequency of sound is produced and so the voice sounds funny.

"Anyone who has never made a mistake has never tried anything new." -Albert Einstein

[Quantumcat]

That's exactly what I would have said, hopefully we are right

Am I dead? Am I alive? I'm both!

[nilmot]

Mmm... interesting suggestion.

So If I inhale lighter air e.g. Hydrogen, would that make my voice go funny as well?

Tom

[chris]

If you're going to do the experiment, I wouldn;t smoke afterwards !

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[nilmot]

KABOOM!!!! []

P.S I don't smoke anyway Chris.. []

Tom

[NakedScientist (OP)]

Here is the answer to last week's QOTW - "WHY DOES HELIUM MAKE YOUR VOICE GO FUNNY ?"

Most of you are on the right lines :

If you imagine your throat as a bit like an organ pipe, when the organist plays a note, one cycle of a wave, with a wavelength approximately the length of the tube, is generated inside the pipe. So when you talk you produce sound waves with wavelengths determined by the length of your throat.

The speed of a wave (c) is given by multiplying the wavelength and the frequency together (c=l.f) and this can be re-arranged to find the frequency of the sound wave (in other words how high it sounds) (f), thus : "frequency = speed divided by wavelength" or f=c/l.

But helium is less dense than the other consitutents of air and so sound travels much more quickly in helium (900 metres per second) than in air (350 metres per second). Substitute these numbers into the forumla we got above (f=c/l) and you get a value for f (helium) 2.5 times greater than f (air). As a result you voice sounds 2.5 times higher when you breathe helium.

Conversely, if you were to breathe a denser gas than air you could make your voice sound much lower.

Divers breathing a helium-rich mix (to overcome the problem of increased gas density at extreme depths) talk to their support crew using a "helium voice unscrambler" which reinforces the lower notes in their voices whilst suppressing the higher tones so that they can be understood.

TNS

[NakedScientist (OP)]

This week's QOTW was submitted by Tom :

"WHEN WE SAY ARSENIC / MERCURY / CYANID ARE POISONOUS, WHY ARE THEY POISONOUS ? "

Over to you !

TNS

[Donnah]

For mercury:

-vaporizes slightly at room temperature
-vapor is odorless/colorless/extremely toxic
-cumulative poison
-crosses blood/brain barrier
-accumulates in brain's pain centre and central nervous system
-prevents normal entry of nutrients into cells
-prevents removal of wastes from cells
-binds to immune cells and impairs function

I'd like to see the biology and chemistry wizards give a more technical view.

Now for my own rant.

Mercury
-is sometimes a component in innoculations (thermisol)
-trivalent innoculations (DPT, MMR) sometimes cause autism
-normally comprises more that 50% of amalgam (silver) dental fillings
-duh!!!!

[cuso4]

Yay, just glad that me and quantum got the helium question correct. Right here goes my answer:

The three substances work similarly. They all affect the electron transport chain (also called oxidative phosphorylation) of cellular respiration. If a cell cannot make ATP, the cell will die.

Arsenic, mercury and cyanide all can inhibit mitichondrial enzyme so that the normal substrate cannot bind. A vital reaction in the process will stop and disrupt the respiration. In the case of cyanide, it inhibits the enzyme cytochrome oxidase.

Furthermore, cyanide and carbon monoxide are respiratory inhibitors which can bind permenantly to haemoglobin preventing it bind with oxygen. This explains why a poinsoned person get breathless. If exposed to large dose, the person can soffocate and die.

Angel

"Anyone who has never made a mistake has never tried anything new." -Albert Einstein

[nilmot]

Ooh, we are getting some pretty good answers here.

And also thanks TNS, for putting my question on the forum.[]

Tom

[NakedScientist (OP)]

HAPPY NEW YEAR EVERYBODY.

HERE'S THE FIRST QOTW FOR 2004, SENT IN BY PAUL SANDKUIJL.

"When you are woken up by a sound and that exact same sound was part
of your dreams ie. the alarm clock, did you begin dreaming your dream
as a result of the sound or were you already dreaming and that sound
became part of your dream?"

DOES ANYONE ELSE EXPERIENCE THIS, AND IF SO, WHY ?

TNS

[bezoar]

Yes, I've had it too, and I always thought the noise triggered the dream.  What was stranger is that when my girls were babies, I always woke up before they did at night, and I would lie still and try to go back to sleep, and invariably they woke up too.  I was never sure if I awakened because I knew they were about to, or if they awakened because they sensed I was awake.

Bezoar

[tweener]

I incorporate external sounds into my dreams all the time.  I think the sound is incorporated, but sometimes it seems the other way around.  Once a dream took it to an extreme:  The alarm was beeping, and I turned it off.  But it wouldn't quit beeping, so I banged the clock on the nightstand.  Then I unplugged it, and it still kept beeping.  Then I removed the cover and started tearing components from the board, and it still kept beeping.  Finally, I had it stripped down to a single little "box" that was beeping, with no apparent power source.  I was really tired by the time I finally came awake.

Nancy,
Babies are very sensitive to their parent's breathing and emotional status, even when they are asleep, so I think they probably woke up because you were awake.  Also, you may have awakened because they changed their breathing pattern before waking, so it may have been a "feedback" scenario.  It is amazing how aware we are even when asleep.


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John