Coin Problem.

[xilman]

Originally Posted by davieddy

But it at least sets a soluble well defined problem,
apparently tricky enough to confuse certain frequent posters
(who shall remain nameless :)
David

Indeed. My contribution to that particular version was to point out that the posters had not defined that problem well enough. If they had used words to the effect 'with each edge chosen with probability 0.5' I would not have been able to conclude that the probability distribution for the problem as stated was 2:1:0.

Paul

[davieddy]

Originally Posted by xilman

Indeed. My contribution to that particular version was to point out that the posters had not defined that problem well enough. If they had used words to the effect 'with each edge chosen with probability 0.5' I would not have been able to conclude that the probability distribution for the problem as stated was 2:1:0.

Paul

Although by and large Mally deserves all the stick he gets.
in this instance he was merely considering the critcal case
where the C of G lay above the border between the "edge" and one
of the faces.

If we include the boundary with the other face. we get 0:1:2 to give a total of 2:2:2 as required.

I don't think we should try to deliberately misunderstand
each other simply to score points.

David

[xilman]

Originally Posted by davieddy

Although by and large Mally deserves all the stick he gets.
in this instance he was merely considering the critcal case
where the C of G lay above the border between the "edge" and one
of the faces.

My point exactly!

The critical word is one of the faces. You must consider both faces and you must specify that each is equiprobable, otherwise you get the "wrong" answer.


The message to take away is one that is applicable throughout mathematics: you must specify the problem completely or you will get a range of answers. Of course, some problems intrinsically have a range of answers...


Paul

[mfgoode]

This problem has been resurrected and is now being played like a broken or cracked record. Lets forget the hypothetical cases and stick to the data given.
Well I claim that the tossing of the coin is also affected by the star Sirius when the earth is at its aphelion. Believe it or not!
Mally

[xilman]

Originally Posted by mfgoode

This problem has been resurrected and is now being played like a broken or cracked record. Lets forget the hypothetical cases and stick to the data given.
Well I claim that the tossing of the coin is also affected by the star Sirius when the earth is at its aphelion. Believe it or not!
Mally

I believe you, if by that statement you mean that if the experiment were to be performed with a physical coin, the dynamics would be different at various relative positions of Sirius and the coin.

However, the effect of the gravitational field and/or the radiation pressure exerted by Sirius, compared with that at any other time, would be immeasurably small.


Paul

[davieddy]

Originally Posted by mfgoode

This problem has been resurrected and is now being played like a broken or cracked record. Lets forget the hypothetical cases and stick to the data given.
Well I claim that the tossing of the coin is also affected by the star Sirius when the earth is at its aphelion. Believe it or not!
Mally

Your description of the problem in the first post could not
have been vaguer.

When split into a series of well defined smaller problems we
find much that is instructive, that hadn't come to light previously
in the thread partly through your perpetual bickering. This [via Drew]
is what brought the thread to my attention in the first place.

Even the dynamcal situation can present a tractable problem,
e.g. by assuming the surface is such that the initial point of contact
is brought to rest.

David

Too many people on this list like to confuse rather than
clarify problems.

[mfgoode]

Originally Posted by davieddy

Your description of the problem in the first post could not
have been vaguer

[Vaguer]
Theres no such word.

When split into a series of well defined smaller problems we
find much that is instructive, that hadn't come to light previously
in the thread partly through your perpetual bickering. [/QUOTE]

I asked for a solution as presented NOT an analysis.

This [via Drew]
is what brought the thread to my attention in the first place.

Hey! lets know who is the side kick, you or Drew?? or are you a split personality?

[ QUOTE=]Even the dynamcal situation can present a tractable problem,
e.g. by assuming the surface is such that the initial point of contact
is brought to rest.[/QUOTE]

The problem is both static (when at rest), dynamical when flipped.

Too many people on this list like to confuse rather than
clarify problems.

Yeah starting with you and your side kick.

My advice: leave Applied mechanics (or go in for a formal training) alone and stick to pure math.

Mally

[mfgoode]

Originally Posted by xilman

I believe you, if by that statement you mean that if the experiment were to be performed with a physical coin, the dynamics would be different at various relative positions of Sirius and the coin.

However, the effect of the gravitational field and/or the radiation pressure exerted by Sirius, compared with that at any other time, would be immeasurably small.


Paul

I am at a loss to know what do you mean by a 'physical coin' ?

Are there any other coins, mathematical or imaginary that exist ?

Ah Sirius ? it was just jib but come to think of it I did not describe the size of the coin. What if it was as big as one of Saturn's rings?

Mally

[DJones]

Originally Posted by mfgoode

Vaguer
Theres no such word.

http://dictionary.reference.com/browse/vaguer
http://www.m-w.com/dictionary/vaguer
http://www.answers.com/vaguer
It's an adjective meaning "more vague". If you're going to claim that a word doesn't exist, at least have the courtesy to check such things first. I appreciate that not everyone on here as English as a primary language, and I generally ignore spelling and grammar errors (unless they make a fundamental difference to the question being asked or the statement being made, in which case I ask for clarification) but to pompously proclaim that a word doesn't exist when no less than three online English dictionaries (not to mention the somewhat authoritative OED) give clear and identical definitions of it is absurd in the extreme.

[mfgoode]

Originally Posted by DJones

http://dictionary.reference.com/browse/vaguer
http://www.m-w.com/dictionary/vaguer
http://www.answers.com/vaguer
It's an adjective meaning "more vague". If you're going to claim that a word doesn't exist, at least have the courtesy to check such things first. I appreciate that not everyone on here as English as a primary language, and I generally ignore spelling and grammar errors (unless they make a fundamental difference to the question being asked or the statement being made, in which case I ask for clarification) but to pompously proclaim that a word doesn't exist when no less than three online English dictionaries (not to mention the somewhat authoritative OED) give clear and identical definitions of it is absurd in the extreme.

I did! In the RD 3 volume enclopaedia before I put that remark.
New words are coming up every day so it is a moot point. It depends on which side of the Atlantic you are

Mally

[davieddy]

Originally Posted by mfgoode

My advice: leave Applied mechanics (or go in for a formal training) alone and stick to pure math.

A first in theoretical phsics (Oxford 1971], Part III Maths Tripos[Cambridge 1972] and 15 years of teaching at St Paul's.Then programmed.I think I can be trusted to talk sense on the subjects.I'm happy to be judged on the strength of my posts though.BTW I was actually defending your 2D approach to thestatic coin problem - something you failed to doeffectively for yourself, hence the slanging match with Drew.David