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12 May 2024 23:18:33 EDT (-0400)
  True shape of VERTICAL rope curve (Message 1 to 6 of 6)  
From: Bald Eagle
Subject: True shape of VERTICAL rope curve
Date: 22 Sep 2017 13:05:01
Message: <web.59c541d96f227fedc437ac910@news.povray.org>
I tried looking this up and I didn't see anything that addressed this:


Let's suppose you're holding one end of a freely hanging rope.
Then you start to give it some rotation by revolving the part you're holding
around the y-axis.
Get it going so that you're twirling it around (it will happen at a harmonic
frequency) and it curves outward [the free end likely crossing over the y-axis].

I was just idly wondering if the shape of that curve would be a catenary.
 ... and if it's the same curve that results from imparting a simple harmonic
motion to it in a plane while it's dangling freely.


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From: omniverse
Subject: Re: True shape of VERTICAL rope curve
Date: 22 Sep 2017 15:10:00
Message: <web.59c55efe48fc86359c5d6c810@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> I tried looking this up and I didn't see anything that addressed this:
>
>
> Let's suppose you're holding one end of a freely hanging rope.
> Then you start to give it some rotation by revolving the part you're holding
> around the y-axis.
> Get it going so that you're twirling it around (it will happen at a harmonic
> frequency) and it curves outward [the free end likely crossing over the y-axis].
>
> I was just idly wondering if the shape of that curve would be a catenary.
>  ... and if it's the same curve that results from imparting a simple harmonic
> motion to it in a plane while it's dangling freely.

Lasso ropes came to my mind, and I thought it might be a kind of sine wave with
increasing amplitude and frequency.
But not knowing anything of the math for such a thing I search the 'net and
found this (math shy people be warned!):

https://physics.stackexchange.com/questions/22268/shape-of-rotating-rope-lasso-problem


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From: Bald Eagle
Subject: Re: True shape of VERTICAL rope curve
Date: 22 Sep 2017 16:45:00
Message: <web.59c575af48fc8635c437ac910@news.povray.org>
"omniverse" <omn### [at] charternet> wrote:

> Lasso ropes came to my mind, and I thought it might be a kind of sine wave with
> increasing amplitude and frequency.

I found plenty of lasso results in my search, but nothing that seemed to point
to the shape of the curved _upper_.


> But not knowing anything of the math for such a thing I search the 'net and
> found this (math shy people be warned!):
>
>
https://physics.stackexchange.com/questions/22268/shape-of-rotating-rope-lasso-problem

Well done, Bob!   :D
Having successfully wrestled with the catenary, I'll have to play with _this_ at
some point in the future.

https://en.wikipedia.org/wiki/Troposkein

[X] I learned something new today.


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From: Stephen
Subject: Re: True shape of VERTICAL rope curve
Date: 22 Sep 2017 16:54:32
Message: <59c57888$1@news.povray.org>
On 22/09/2017 21:42, Bald Eagle wrote:
> https://en.wikipedia.org/wiki/Troposkein
> 
> [X] I learned something new today.

It doesn't have a good a name as the Blancmange curve. ;-)

https://en.wikipedia.org/wiki/Blancmange_curve


-- 

Regards
     Stephen


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From: omniverse
Subject: Re: True shape of VERTICAL rope curve
Date: 24 Sep 2017 16:50:00
Message: <web.59c819e648fc86359c5d6c810@news.povray.org>
Stephen <mca### [at] aolcom> wrote:
> On 22/09/2017 21:42, Bald Eagle wrote:
> > https://en.wikipedia.org/wiki/Troposkein
> >
> > [X] I learned something new today.
>
> It doesn't have a good a name as the Blancmange curve. ;-)
>
> https://en.wikipedia.org/wiki/Blancmange_curve

Pudding, eh? Everything should be named after something else. LOL

Made me look at it, what a great subject matter for a rendering, as seen here:

https://en.wikipedia.org/wiki/Blancmange#/media/File:Blanc-manger_on_glass_platter.jpg

That Troposkein curve reminds me of myopia since I'm near-sighted like most
people who need eyeglasses. Too much bend in the cornea.

BTW, I seldom watch for off-topic messages. Just happened to *see* this one!


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From: Kevin Wampler
Subject: Re: True shape of VERTICAL rope curve
Date: 17 Oct 2017 12:52:38
Message: <59e63556@news.povray.org>
On 9/22/2017 1:42 PM, Bald Eagle wrote:
> Having successfully wrestled with the catenary, I'll have to play with _this_ at
> some point in the future.
>
> https://en.wikipedia.org/wiki/Troposkein
>

Neat!  I was not familiar with the name for that curve.


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