Re: A long time (second time)

[onta...@hotmail.com]

Dare I ask again or is the matter closed Joao ?

[João Pedro Afonso]

> >Dare I ask again or is the matter closed Joao ?
>

> Sorry Bill, I have this bad habit of not reading the
> threads when I'm not able to do them a proper
> followup... leaving them to when I can do that. I
> failed to saw your last questions last time. For the
> ones with a bad news server and not
> affiliate/addressing directly the Drexel Math Forum
> site, this was a puzzle create two years ago based on
> an puzzle presented by Ontadian. It runs like this
>
> "A friend of mine living in Porto-Alegre, Sao-Tome
> and Prince Islands, send me a letter recently:
>
> "Hi Joao, I bought this wonderful simple pendulum
> yesterday. He has an oscillation period of 2 seconds,
> but hear this, if I change its length to 1% more, the
> period is preserved"
> "
>
> I'll write meanwhile a proper solution to post next
> week (giving a last chance, a third, to others)
>
> Cheers,
> JPA

Oops, forgot to add the question:

Q: What is the length of the pendulum?

[João Pedro Afonso]

>Dare I ask again or is the matter closed Joao ?

Sorry Bill, I have this bad habit of not reading the threads when I'm not able to do them a proper followup... leaving them to when I can do that. I failed to saw your last questions last time. For the ones with a bad news server and not affiliate/addressing directly the Drexel Math Forum site, this was a puzzle create two years ago based on an puzzle presented by Ontadian. It runs like this

[gudi]

> depends on local gravity.
> Cheers,
> JPA

The seconds pendulum ( T = 2 secs) has local acceleration g = pi^2
length, so for same period, length

[João Pedro Afonso]

> The seconds pendulum ( T = 2 secs) has local
> acceleration g = pi^2
> length, so for same period, length

Very true :-)

...so, what is the pendulum length?

JPA

[João Pedro Afonso]

A friend of mine living in Porto-Alegre, Sao-Tome and Prince Islands, send me a letter recently:

"Hi Joao, I bought this wonderful simple pendulum yesterday. He has an oscillation period of 2 seconds, but hear this, if I change its length to 1% more, the period is preserved"

Q: What is the length of the pendulum?

**********
Before I present a solution here tomorrow, I want to apologize to Bill (Ontadien) and to anyone who eventually tried to solve this problem. When I proposed this problem two years ago, I made it on a whim to tease other problem proposed in this newsgroup. At the time I saw what I thought to be a beautiful new side to explore, to ask something which were proved false on the original problem. As a followup, what could be more intriguing than prove something wrong and then insist there is situations where it could be right? I even was seeing what kind of solutions could arise and they were beautiful. But,...

..seeing at the distance, I should have been in one of my fantasy moments. Somewhere, I must have screw some basic judgment because the results turned to be more ugly than beautiful. Oh!, there is a solution. One of the reasons I reformulated my original teasing was to assure there was at least a solution even if not the one I thought originally. Tomorrow of after tomorrow, I'll present the ugly solution in which my problem turned to be. But today, I will present the backup solution I introduced in the problem: the pendulum has length 1.51457*10^-8m, about 15.1nm. Care to think how this works? Last chance to put the imagination at work. :-) You don't need to present the calculations, just the ideas. :-)

Cheers,
João Pedro Afonso

[onta...@hotmail.com]

Thanks Joao, for you kind words, although sometimes my desire and enthusiasm to get into print exceeds my capacity to see all the nuances of a problem, and I feel hung out to dry when they come to light. As for this pendulum problem there are many, many aspects to it, and I think now it is time for closure. Tempus fugit.

[João Pedro Afonso]

> feel hung out to dry when they come to light. As for
> this pendulum problem there are many, many aspects to
> it, and I think now it is time for closure. Tempus
> fugit.

Its the same for me. This problem is closed (unless I happen to try a two hour pendulum). I'm going to my summer vacations, and I'm out for a time.

Bye