Things That Go Bang
Threads - Mythbusters
On 24/6/2006, Adam Selinger posted:
This has been a really fascinating discussion on the list.
'Informal'science education is the area I have been involved with for
about 15 years. I just wanted to add two comments:
1. Best 'science' on TV, for me, has to be Myth Busters (Mon 7:30pm
SBS). These two guys, and colleagues, go about investigating myths with
stringent regard for the science method and a great sense of adventure
and passion! A must for all science, technology, maths and design
students.
2. For a great technology workshop (someone already mentioned soldering) see
www.madlab.org I was so impressed with this
learn-to-solder-and-take-way-your-gadget activity from the Edinburgh
International Science Festival that I have helped role it out in Oz.
Really quite easy to run yourself (once you have the gear) or book in
the 'professionals' (e.g. CSIRO Education).
Stephen Watts replied:
I must watch a different series of Mythbusters...
The
other night I was watching them trying to prove some point about a
medievial trebuchet and a car engine. I watched the nonsense for about
5 minutes. I thought it would have been far easier to prove the point
with a pencil and a piece of paper.
Tamara Kelly responded:
I have seen this program twice while at my sister's place and think it's GREAT.
The whole point
is for boys to build things and have a great time blowing things up.
It's not JUST about proving or disproving some idea - it's about
having, big, technical, go bang, FUN.
Who wants to do
it on paper? Most people don't understand the mathematics but they can
understand when it is demonstrated. What I hope is that it makes
non-science people more interested in science and makes them more
skeptical and inclined to give it a go.
have (practical) fun
Cathy Watson added:
I think MythBusters is a fantastic teaching tool. My students watch
it for "homework" every week and come back asking about all sorts of
science concepts. I then encourage them to work in groups to research
the concept in question and to tell me all about it, they can even make
their own models in class if they like.
I find it really appeals to them as it is exciting, fast paced and hey...they blow things up!
I believe that if we can encourage students to think scientifically
(in any way, shape or form), then we are doing them a favour and then
this will encourage them to work things out with pen and paper later.
Justin McGuire commented:
It may have been
simple to disprove the myth using a pen and paper, but "Jamie and Adam
do algebra" doesn't make for good television. TV is a visual medium and
I think the approach Mythbusters takes is very well suited to that
medium.
Another thing I like about the show is that they always do the experiment, even if I don't always agree with their methodology.
The downside of
relying on a mathematical model is that your results are only as good
as your model. A good example is the one where they compared driving
with air conditioning on to driving with windows open. They started by
feeding data from test drives into a computer model, which showed AC
was more efficient. However, when they actually tried driving two
similar cars using the same amount of fuel, the one using AC ran out of
fuel much earlier than the other one. While I have some issues with the
methodology they used in this experiment, it certainly showed there
were holes in the computer model.
Suzanne Dunn noted:
It
may have been simple to disprove the myth using a pen and paper, but
"Jamie and Adam do algebra" doesn't make for good television. TV is a
visual medium and I think the approach Mythbusters takes is very well
suited to that medium.
Another thing I like about the show is that they always do the experiment, even if I don't always agree with their methodology.
Garry Dalrymple wrote:
On Anna's favourite TV show they had a piece on exploding farmers trousers, apparently, and they were _very_
coy about exactly what the chemical was, the use of a '1930s pesticide
in New Zealand' resulted in trousers / overalls exploding into flame.
They
demonstrated the effect, they compared the effect with some home made
gun cotton (nitro cellulose), black powder and even the Fe/Al
Hindenburg coating. The pesticide soaked into cotton cloth visibly
burned faster than these.
My question is -
what on earth are they talking about? What sort of a chemical like that
could make it onto the market in even a third world country like NZ in
1930?
Any suggestions? Could make a haka more interesting!
The downside of
relying on a mathematical model is that your results are only as good
as your model. A good example is the one where they compared driving
with air conditioning on to driving with windows open. They started by
feeding data from test drives into a computer model, which showed AC
was more efficient. However, when they actually tried driving two
similar cars using the same amount of fuel, the one using AC ran out of
fuel much earlier than the other one. While I have some issues with the
methodology they used in this experiment, it certainly showed there
were holes in the computer model.
Peter Macinnis replied:
I think potassium chlorate was used as a weed killer. Or maybe it was
potassium perchlorate -- each is a powerful oxidising agent, though
perchlorate is better in any bangs-for-a-buck sense. JATO units in
World War II were asphalt and potassium perchlorate, and those certainly
packed a punch.
Older readers may recall that the IRA were said to use bombs that
incorporated 'weed killer' -- and the authorities were equally coy about
that. I am fairly sure that the perchlorate was NOT used as a weed
killer, though it probably could have been. I have a vague idea that
the other half of the IRA formulation was sugar, which I think it is OK
to say, since neither of the oxidising agents is available legally, and
people knowing where to get the stuff illegally probably have all the
information they need.
Paul Williams answered:
<snip>
My question is - what on earth are they talking about? What sort of a
chemical like that could make it onto the market in even a third world
country like NZ in 1930?
<snip>
Sodium Chlorate.
Science show 2004 - Interview with James Watson (Massey, N.Z) on this:
http://www.abc.net.au/rn/scienceshow/stories/2004/1264069.htm#
Watson later won an Ig Nobel prize (2005) for:
"The Significance of Mr. Richard Buckley's Exploding Trousers:..."
Abstract (which doesn't mention exploding trousers) :
http://caliber.ucpress.net/doi/abs/10.1525/ah.2004.78.3.346;jsessionid=oX6gNCvtL5L6?cookieSet=1&journalCode=ah
Or:
http://tinyurl.com/y4umqt
Brian Lloyd responded:
On Anna's favourite TV
Great show. It is one of the few reasons for still having a TV set.
show they had a piece on exploding farmers
trousers, apparently, and they were _very_ coy about exactly what the
chemical was,
They didn't want Junior trying this one at home.
the use of a '1930s pesticide in New Zealand' resulted in
trousers / overalls exploding into flame.
They demonstrated the effect, they compared the effect with some home
made gun cotton (nitro cellulose), black powder and even the Fe/Al
Hindenburg coating. The pesticide soaked into cotton cloth visibly
burned faster than these.
Pretty cool, huh!
My question is - what on earth are they talking about? What sort of a
chemical like that could make it onto the market in even a third world
country like NZ in 1930?
Any suggestions? Could make a haka more interesting!
Also,
They had 'tallow' rockets, American civil war technology apparently.
Apply heat and some Nitrogen oxide and you can make greasy
smallgoods in
a rocket casing go 'Whoosh' (Weapons of Meat destruction, Pork rockets
against Al Kaida?). Very impressive but I didn't catch the details.
They build a compound solid/liquid fuel rocket using a pipe casing,
some candle wax (what we call paraffin here in the US, not kerosene)
for fuel, and liquid nitrous oxide as an oxidizer. The bloody thing
actually worked and flew several hundred feet. The myth was the the
Confederate army built ballistic rockets that traveled about 200KM.
So they proved that using period hardware they could have constructed
a rocket but that they could not have reached 200KM. Myth busted.
They neglected that the idea for the technology wasn't around then.
Still, the rocket was WAY COOL. I probably couldn't get away with
doing that with my elementary science class tho'. <sigh>
Peter Macinnis commented:
By that, you mean the technology for liquid fuel rockets, I assume. I
think Tsiolkovsky may have been the first to come up with that -- he was
born in 1857, so you may be right.
There were certainly plenty of solid fuel rockets back then, but they
were generally regarded as unreliable. The Austrians used them a lot,
because they had many mountainous parts of their empire where people
wanted them out and rockets were lighter than artillery. The British
boats used rockets as close-range "artillery" in landings during the
Crimean War, but all were powered by special gunpowder formulations.
We will pass over the unfortunate contretemps at Fort McHenry, where
only the bombs ever came close to having an effect. Likewise
Copenhagen, the Battle of Nations at Leipzig and certain skirmishes in
the Peninsular War. All of those used gunpowder rockets.
I think we could probably add that liquid nitrous oxide was a bit rare
at the time of the US Civil War -- which Americans, in their
self-centred way, persist in calling "the Civil War", as if there were
no others.
The launch method used in Edward Everett Hales' _The Brick Moon_
(http://www.gutenberg.org/etext/1633), two water-powered flywheels,
might have been used to throw stuff, but I think Hale was a Northerner,
considering his given names. (Yup -- a Bostonian.)
Terry Hyland observed:
Hi all.I know you don't celebrate Thanksgiving so have you ever heard of beer can turkey? or hair spray rockets. you spray the hair spray in a bottom hole shove potatos in the tubes.Then stand back after you ignite.they fly quite far.this I,m sure of the alcohol content.there meant as pranks.same with the turkey bombs,the go quite far.
Alan Emmerson enquired:
Have we forgotten William Congreve's iron rockets that were used to bombard Boulogne in 1805?
and:
Did the chemical have to be a weed killer? Perhaps it was another sort of agricultural chemical.
The performance of the trousers rather sounds as though they had been soaked in a saltpetre solution. A bit like a fuse.
Incidentally, I
was interested to read last week that a compound we employed in
schoolboy pranks involving sharp bangs and purple brown stains was
being used as some sort of detonant by the nasty buggers. Tricky stuff
when dry. I wonder how many have lost hands.
Terry Hyland noted:
have we forgetting the Spanish Amanda--with there less the desirable cannon balls
Peter Macinnis responded:
No, Alan, we had
not forgotten it -- or, at least I hadn't. How could I forget
what did not happen? In the strict sense, Boulogne was never
bombarded at all, but there was absolutely no rocket attack on Boulogne
or its port and environs in 1805. One was planned, but then
called off because the weather was bad. You are correct on one
point: the
Congreves used later (not in 1805) to attack Boulogne were the same ones used at Copenhagen, Leipzig and Fort McHenry.
I assume you
were thinking of the attempt to attack the French fleet at Boulogne in
1806 (October 7-8). Most of the rockets missed the fleet and hit
the town, but Boulogne was not the target. That being so, it is
rather less than precise to speak of bombarding Boulogne.
Equally, there
was no rocket attack on Cadiz, though Nelson proposed it, just before
Trafalgar, in a letter to Canning of October 1, 1805 -- though the idea
was to force the ships sheltering there out of the harbour. Once
Nelson died, Wellesley was able to operate his bias against the
Congreves in many spheres.
Nothing was
forgotten -- I kept it brief and referred to the salient points
only. That is why I left out Boulogne, the Netherlands, and a few
other uses.
Alan Emmerson wrote:
Thanks for the info Peter. Learn something everyday.
On the question of liquid fuel rockets, did Ziolkovski actually produce any hardware?
I thought his contribution was in the mechanics of space flight and that Goddard was the first with the hardware.
Brian Lloyd responded:
By that, you mean the technology for liquid fuel rockets, I assume.
Yes. Solid-fuel rockets have been around for about two millenia. I
was speaking of working, liquid-fuel or compound (liquid/solid fuel)
rockets. Robert Goddard is the first I know of to have constructed a
working liquid-fuel rocket.
I think Tsiolkovsky may have been the first to come up with that --
he was born in 1857, so you may be right.
I wasn't aware that he constructed a working rocket.
I think we could probably add that liquid nitrous oxide was a bit
rare at the time of the US Civil War -- which Americans, in their
self-centred way, persist in calling "the Civil War", as if there
were no others.
I think it mostly has to do with familiarity of terms rather than an
attempt to slight anyone else. The term "the Civil War" has been used
for many generations so it is what naturally rolls off the lips. I
think you are attributing more thought to the action than anyone here
bothers to give it.
Heck, most people here want to call the US of A "America". Whenever I
hear that I wonder about the Canadians, the Mexicans, and the people
of Central and South America. Regardless, I think there is a lot more
"familiar use" than intention in its application.
The launch method used in Edward Everett Hales' _The Brick Moon_
(http://www.gutenberg.org/etext/1633), two water-powered flywheels,
might have been used to throw stuff, but I think Hale was a
Northerner, considering his given names. (Yup -- a Bostonian.)
Allegiances did not fall strictly on geographic boundaries in that
war. (1861)
and:
Incidentally, I was interested to read last week that a compound we
employed in
schoolboy pranks involving sharp bangs and purple brown stains was
being used as some
sort of detonant by the nasty buggers. Tricky stuff when dry. I
wonder how many have
lost hands.
Nitrogen tri-iodide (NI3). All you need to do is dump iodine into
ammonia. NI3 is what precipitates out. I think most schoolboys
experiment with that at one time or another. It is so unstable I
would never consider using it as a primer.
Heck, when I was making it I would filter the precipitate from the
liquid using filter paper and then I would lay out the filter paper
to dry. Every evening I would come home to find it had detonated
leaving a stain on the kitchen counter to clean up before my mother
saw it. One day I discovered the problem: the sun would reach my
filter paper and set it off. From then on I dried it in a dark place.
So if something is so unstable that mere sunlight can set it off, it
sure as heck is too unstable for anything but small concentrations
used for fun.
Anthony Morton replied:
That'd be the stuff all right. But with my pedant's hat on, I have a
vague recollection that tri-iodide is univalent, which means the
formula is actually N(I3)3. Wierd stuff indeed.
Gerald Cairns posted:
Reminds me of an
incident in Chem 1 at Sydney Uni where one student made a significant
quantity NI3 and left it in his cupboard to dry during vacation. The
inevitable happened and it was fortunate that only a chem lab bench was
destroyed.
It wasn't me by the way.
When working
with a new refining process in the mid 1980's I did manage
unintentionally to create Ag salts in small amounts around the meniscus
of the S/S vessel and each time the stirring rod touched the meniscus
it would create a small but powerful detonation. It was decided that
this process was too unstable to risk scaling up. We did not pursue the
identification as explosives were not our aim but Ammonium Ag salts
were suspected.
Brian Lloyd responded:
> It wasn't me by the way.
Of course not.
When working with a new refining process in the mid 1980's I did
manage
unintentionally to create Ag salts in small amounts around the
meniscus of
the S/S vessel and each time the stirring rod touched the meniscus
it would
create a small but powerful detonation. It was decided that this
process
was too unstable to risk scaling up. We did not pursue the
identification
as explosives were not our aim but Ammonium Ag salts were suspected.
Well, things that explode are "guy" things.
Alan Emmerson commented:
And there was I trying to be discreet about the chemical formulation in case the potentially bad buggers could read..
Gerald Cairns replied:
Not
sure which message you are tongue in cheek replying to, mine about
AmmoniumAg salts or Ammonium tri iodide but I wouldn't worry too much
on that account those substances are so bloody unstable the bad buggers
would likely blow themselves up trying to work with them - ionic
justice you might say.
I think they know heaps enough without our contributions so far.
Alan Emmerson answered:
It was the
ammonium tri iodide Gerald. The ingredients were in a list of
substances recovered from a terrorist group and I was surprised that
they seemed to be using it , for just that reason.
Mind you there have been some horrendous accidents with ammonium nitrate too.
Ray Stephens responded:
Ammonium tri iodide 'could' make a detonator for something otherwise more
stable.
If it had a point, which it never does outside mining, demolition, road
building, or pyrotechnics for entertainment.
Garry Dalrymple wrote:
This sounds a lot like the stuff used in the munitions on Edgar Rice Burroughs' Barsoom (Mars).
They were
powered by the 'Eighth Ray' (i.e. a theosophical light/energy beyond
the seven colours of the terrestrial rainbow) as was everything else on
Barsoom, but on the morning after a battle it was very dangerous to
still be on the battlefield as unused or abandoned ammunition detonated
when touched by light as the Sun rose.
Gerald Cairns replied:
I
seem to recollect that it was painted on the door handles of the car of
I think Arthur Calwell NSW Labor Premiere and some others while he was
at a function in Mosman many years ago. Apparently someone brushed up
against one door and detonated the stuff doing considerable damage to
the door handle and maybe someone actually suffered injury too. When
the police arrived one officer touched a door handle with his torch and
destroyed it.
This is the best of my memory of that fading era. Terrorism ain't new!
Even a fly walking on it can set it off.
Ray Stephens noted:
Picric Acid was one of the substances of choice in WWI munitions, I believe,
and this too is also a highly unstable stuff in its dehydrated form.
ftr, it is also used (with extreme care and spillage control) in histology
as a tissue stain.
