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Galimaufrey & coca cola

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Senor Freebie
918397.  Thu Jun 21, 2012 5:29 am Reply with quote

I'm a bit worried by one of the pieces of commentary re: Coke & Teeth. As a science experiment in High School our teacher did this one with our class. We had a tooth in a glass of coke for 2 days (between science classes) and it did indeed dissolve. Not completely, but it was half the size. As we had a class in another subject in the same lab the intervening day we saw the tooth partially dissolved. Maybe, the tooth was weakened already, hence being available ... or the coke from the plastic bottle had already been mixed with some stronger acid, but I find this unlikely since the Ph of coke is high enough to achieve this anyway.

The scientist who stood up in front of your House of commons and said this appears to have been correct and to argue against that seems to be to argue for something that is slightly toxic. I still drink coke, just as I drink alcohol and smoke ... but I'm under no illusion that it doesn't dissolve my teeth.

 
'yorz
918431.  Thu Jun 21, 2012 7:30 am Reply with quote

As I may have mentioned before - I was told in school that in order to determine whether your mother's heirloom pearl necklace is the real McCoy is to immerse it overnight in Coke. If it has dissolved by the next morning, then it was.

 
Jenny
918466.  Thu Jun 21, 2012 9:10 am Reply with quote

Welcome to the forums Senor Freebie - just don't drink Coke. You know it makes sense...

 
dfinagle
1014661.  Fri Aug 02, 2013 9:57 am Reply with quote

On the show, it was stated that although blindfolded people will always fail to walk in a straight line, the reason for it was unknown.

My father told me that in his experience in World War II, when there was going to be a column of twos. It was always contrived to have a right handed person and a left handed person leading the column. The reason for this was that anyone attempting to walk straight would be put off by the sllightly longer stride on his dominant side. Pairing opposite handed soldiers at the column's front would even out the action resulting in a straight march. Their natural incllinations served as a check on each other's errors.

 
suze
1014668.  Fri Aug 02, 2013 10:48 am Reply with quote

The tendency is to veer off clockwise whether one be right- or left-handed, but people who instead veer off anticlockwise tend to be left-handed.

Given that information, which way around should the right- and the left-hander stand at the front of the column?

 
Jenny
1014682.  Fri Aug 02, 2013 1:16 pm Reply with quote

The left hander on the right, surely - but I guess you'd have to blindfold a group of left handers and watch which way they veer to be sure of choosing the correct left hander!

 
PDR
1014685.  Fri Aug 02, 2013 1:34 pm Reply with quote

suze wrote:

Given that information, which way around should the right- and the left-hander stand at the front of the column?


I'd suggest they both stand facing forwards, because walking sideways is very tiring.

:-)

When crossing open terrain the military don't rely on peoples' ability to walk in straight lines at all for precisely this reason - they march with respect to a compass bearing or landmarks. If they are in a featureless bit of terrain without a compass then they use the time and the sun for reference; or they march at night (resting up during the day) so that they can use stars as a reference.

Infantry are taught all sorts of navigation methods, including keeping counts and tallies of paces to keep track of distance covered. With practice these can be remarkably accurate - certainly to a couple of hundred yards in ten miles.

These techniques are still practised for the same reason that the navy still teach compass/sextant/chronometer navigation - it avoid having to rely on technology that might be spoofed or broken when it's needed.

PDR

 
suze
1014702.  Fri Aug 02, 2013 4:19 pm Reply with quote

Jenny wrote:
The left hander on the right, surely.


I spent a few minutes thinking about this earlier, but "convinced" myself of both possible answers.

Since then, a certain amount of rather good red wine may have been taken - and so I can now think straight! Accordingly, I think you're correct - much as PDR tells us that it wouldn't actually be organized this way.


Now, a question. Suppose that I am indeed in open terrain without a compass, and am attempting to walk to a distant landmark. If I just aim myself at that landmark and keep going, will I then go towards it in a straight line? Or will I still tend to veer off to clockwise, and have to re-target myself from time to time? (For the purpose of this question, the red wine may be ignored.)

 
Efros
1014709.  Fri Aug 02, 2013 5:52 pm Reply with quote

Coca Cola has a pH of about 2.5, the base pH of stomach acid is about 1.5. Tooth erosion is one of the markers for people using vomiting to control weight. Any acid will attack teeth, if you did the same experiment with malt vinegar you would see almost the same effect as with Coca Cola. Apple juice and tomato ketchup will do the same although it will take longer, ph of about 3 and 4 respectively. TBH I don't believe the Coca Cola experiment shows anything other than that acid will dissolve teeth, everything we drink, other than water, is acid to a greater or lesser degree, but usually we don't hold it in our gobs for 2 days. To minimize the effect you should drink through a straw as this lessens the erosion of the front teeth and you also tend to swill the liquid around your mouth less when using a straw.

 
PDR
1014730.  Sat Aug 03, 2013 3:06 am Reply with quote

suze wrote:
Accordingly, I think you're correct - much as PDR tells us that it wouldn't actually be organized this way.


I think the real point is that these days infantry won't cross terrain by forming up into ranks and marching as a column - that went out after Napoleonic times. They might travel down roads like that, although even there it's far more likely that they'd move in loose formation at the sides of the road because (a) it's less vulnerable to air and artillery attack and (b) an open formation allows each soldier to freely use his/her eyes and weapons. So it becomes a thought experiment only.

Quote:

Now, a question. Suppose that I am indeed in open terrain without a compass, and am attempting to walk to a distant landmark. If I just aim myself at that landmark and keep going, will I then go towards it in a straight line? Or will I still tend to veer off to clockwise, and have to re-target myself from time to time? (For the purpose of this question, the red wine may be ignored.)


It depends how often you re-check against the landmark. If you only look at it every ten minutes or so then you'll veer when you're not looking at it - probably more because you're avoiding lumps in the ground, bushes, rocks etc, or taking an easy route up short slops etc than due to the anatomical explanations. The "standard veer" is (as I understand it) something of a theoretical concept that might apply only where the terrain is truly flat and featureless - like a 500 mile bowling green. There will be so many other influences on where each next step is placed that this very small bias will be swamped by the others.

Again, going back to the military example - from what I remember the approach trained by the infantry is to allocate roles to members of a squad. At least two will be pace-counters who will be focussing on maintaining the count and trying to walk the straightest line. They have techniques like doing the pace count in blocks of a hundred and then transferring a small pebble, match or other object from left pocket to right pocket. Every ten blocks of a hundred they will have another marker or update the plot on the squad-leader's map. This is practiced in squads and each soldier will have establish what their typical personal "paces per mile" number is for different types of terrain. On smooth, hard ground a thousand paces for a 6' soldier will be about half a mile, but on soft sand, snow or moorland it will be between a quarter and a third of a mile. Knowing what these numbers are ios part of the professional skills of the infantryman.

Another two will be doing the navigation - ensuring that the whole squad is moving in the required direction by near-constant reference to landmarks, stars or compass. Others will be allocated defensive observation roles (constantly looking for hazards both near and far) and others will be allocated "intelligence observation" roles, looking around and seeing of there is anything of interest that they should be taking account of. This whole approach does two things - it maximises the effectiveness of the squad by allowing each to concentrate on a specific task rather than trying to do everything) and it gives each person their own "mission" to keep them awake and alert.

The stories of people walking in circles in the desert also have other explanations - there is an inherent subconscious tendency to walk in a constant bearing to the sun or moon, which (of course) moves through the day.

PDR

 
Spud McLaren
1014752.  Sat Aug 03, 2013 7:59 am Reply with quote

suze wrote:
Now, a question. Suppose that I am indeed in open terrain without a compass, and am attempting to walk to a distant landmark. If I just aim myself at that landmark and keep going, will I then go towards it in a straight line? Or will I still tend to veer off to clockwise, and have to re-target myself from time to time? (For the purpose of this question, the red wine may be ignored.)
This will depend on how you walk - whether you actually turn slightly right as you veer right (in which case the answer to your second question, assuming you keep the landmark in view constantly, is no), or whether you are actually walking slightly sideways all the time but still pointing your body toward the landmark (in which case the answer is yes; your course will describe a constantly-tightening curve).

Edited for clarity (I hope)


Last edited by Spud McLaren on Sat Aug 03, 2013 8:47 am; edited 1 time in total

 
Spud McLaren
1014754.  Sat Aug 03, 2013 8:12 am Reply with quote

PDR wrote:
When crossing open terrain the military don't rely on peoples' ability to walk in straight lines at all for precisely this reason - they march with respect to a compass bearing or landmarks. If they are in a featureless bit of terrain without a compass then they use the time and the sun for reference; or they march at night (resting up during the day) so that they can use stars as a reference.
Using a compass won't necessarily eliminate veering, because of the second of the scenarios above. Walking slightly sideways will cause you to veer without knocking you off-bearing, unless you have a landmark to site on - and even then it won't be apparent until you're quite significantly off..

Where there are three or more in the party, the best way of crossing featureless terrain is to send two on ahead; have them line up on the bearing at whatever distance (from you and from each other) is practicable, then walk past them, giving the compass to the rearmost man as you pass him. You then walk to a point as far in front of the foremost man as he is in front of the rearmost, and stop. The rearmost man then communicates with the others to fine-tune their line on the bearing, then walks, etc... in this way you can leapfrog your way pretty accurately along the bearing as far as is necessary.

 
PDR
1014757.  Sat Aug 03, 2013 8:34 am Reply with quote

Indeed - there are lots of possible techniques depending on the circumstances.

The point you make about holding a bearing is a good one which I hadn't considered - ideally you want to keep a landmark at a given compass bearing to prevent this I suppose!

PDR

 

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