OT: Slinky Question

"Philip A. Marshall" <philmarshall@hotmail.com> wrote in message
news:rn5k40pmtirls5ftdpd5khu3j509pa0o64@4ax.com...
On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
thegreatone@example.com> wrote:

If you place a Slinky on an escalator, will it go forever ?:)


not if the escalator is going down :)

or if it's going up too quickly
Click to expand...
Or too slowly.
 
On Sat, 06 Mar 2004 13:52:45 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sat, 06 Mar 2004 11:47:47 -0800, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 06 Mar 2004 12:52:27 -0600, John Fields
jfields@austininstruments.com> Gave us:

On Sat, 06 Mar 2004 18:22:59 GMT, Philip A. Marshall
philmarshall@hotmail.com> wrote:

On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
thegreatone@example.com> wrote:

If you place a Slinky on an escalator, will it go forever ?:)


not if the escalator is going down :)

or if it's going up too quickly

---
Or if it's going up too slowly, so we'd need to servo the escalator to
the slinky's period.

Start at the top with the escalator off. When the slinky reaches
the bottom (near it), turn the escalator on, bring the slinky back to
the top, and then turn it off again. No servo, just an on off button
"server". Hehehe...

That's still a servo, hehehe...
Click to expand...
The other interesting part is the longterm stability of the slinky
itself. If it can reach too far, it might wander out on progressive
steps, trip on an edge, and tumble. If it's too short, it may land on
the same step it's on, and die there. I suppose it has to have a step
distance slightly below the tread width and occasionally brush a riser
to apply some longterm centering stability. There are lateral
stability issues, too.

Is a slinky ever longterm stable walking down stairs?

John
 
Paul Burridge wrote:
On Sat, 06 Mar 2004 11:35:57 -0700, Jim Thompson
thegreatone@example.com> wrote:


On Sat, 6 Mar 2004 13:23:31 -0500, "Bill Garber"
willy46pa@comcast.net> wrote:


"Philip A. Marshall" <philmarshall@hotmail.com> wrote in message
news:rn5k40pmtirls5ftdpd5khu3j509pa0o64@4ax.com...
: On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
: <thegreatone@example.com> wrote:
:
: >If you place a Slinky on an escalator, will it go forever ?:)
:
: not if the escalator is going down :)
:
: or if it's going up too quickly

Or turned off, or moving too slowly.

Lots of variable left out Jim. I sort of
remember you complaining about people doing
that with your classroom tests here. 8o)


It's a question "for discussion" ;-)


More of a "thought-provoking metaphysical conundrum" IMV. :)
Click to expand...
Hang on -- a conundrum is a riddle in which a fanciful question is
answered by a pun. Like:

"How is a cat's tail like a long road?"

"Because they are both `fur' to the end."

We got the fanciful question part. Now we need the punnish answer.
/Then/ we'll have a conundrum.

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
On Sat, 06 Mar 2004 14:03:35 -0600, John Fields
<jfields@austininstruments.com> Gave us:

On Sat, 06 Mar 2004 11:45:48 -0800, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 6 Mar 2004 13:23:31 -0500, "Bill Garber"
willy46pa@comcast.net> Gave us:


"Philip A. Marshall" <philmarshall@hotmail.com> wrote in message
news:rn5k40pmtirls5ftdpd5khu3j509pa0o64@4ax.com...
: On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
: <thegreatone@example.com> wrote:
:
: >If you place a Slinky on an escalator, will it go forever ?:)
:
: not if the escalator is going down :)
:
: or if it's going up too quickly

Or turned off, or moving too slowly.

Lots of variable left out Jim. I sort of
remember you complaining about people doing
that with your classroom tests here. 8o)

Also it is a system that consumes about twenty thousand times more
energy than it creates. The slinky doesn't need to "go forever", the
escalator does. Send the electric bill to the OP.

---
Energy can't be created or destroyed, it can only be transformed...
Click to expand...
Or transferred, as in this case. Kinetic energy, and altitude are
the factors.
 
Jim Thompson wrote:

If you place a Slinky on an escalator, will it go forever ?:)
Click to expand...
There are dynamically stable mechanical walking machines that walk and
run downhill, no battery, electronics or FCS required. They could
probably be dressed up for an interesting spectacle.

--
Scott

**********************************

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

http://home.comcast.net/~scottxs/

**********************************
 
I read in sci.electronics.design that Mike Rocket J. Squirrel Elliott
<j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDOT.net> wrote (in
<CPGdnXeDU8ia2tfdRVn-ug@adelphia.com>) about 'OT: Slinky Question', on
Sat, 6 Mar 2004:
We got the fanciful question part. Now we need the punnish answer.
/Then/ we'll have a conundrum.
Click to expand...
OK. The answer is 'I'll take steps to find out.'.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
John Fields <jfields@austininstruments.com> wrote in message news:<otak40tnpcvg735brln36aqprtdnpaiju7@4ax.com>...
On Sat, 06 Mar 2004 11:47:47 -0800, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 06 Mar 2004 12:52:27 -0600, John Fields
jfields@austininstruments.com> Gave us:

On Sat, 06 Mar 2004 18:22:59 GMT, Philip A. Marshall
philmarshall@hotmail.com> wrote:

On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
thegreatone@example.com> wrote:

If you place a Slinky on an escalator, will it go forever ?:)


not if the escalator is going down :)

or if it's going up too quickly

---
Or if it's going up too slowly, so we'd need to servo the escalator to
the slinky's period.

Start at the top with the escalator off. When the slinky reaches
the bottom (near it), turn the escalator on, bring the slinky back to
the top, and then turn it off again. No servo, just an on off button
"server". Hehehe...

That's still a servo, hehehe...
Click to expand...
Yep. A very crude bang-bang controller. In principle you should be
able to tune the speed of the elevator to keep the Slinky in more or
less the same place - it is effectively an oscillator, so that analogy
would be with a phase-locked loop rather than a simple analog control
loop.

In any event it begs the question of how you reliably detect where the
Slinky is. I suppose it is optically dense enough that a
photo-detector would work - I'd think in terms of two bright, fairly
narrow beam leds, one on either side of the escalator, and two pairs
of photo-dectors, about twice the Slinky diameter apart, on either
side of the escalator, flanking the leds.

----------
Bill Sloman, Nijmegen
 
"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?
Click to expand...
No, it will probably get caught in the big crunch or great chill.
Alternatively, someone will trip over it, thereby rendering it no longer a
slinky, and sue everyone in sight.

Bill
 
"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?
Click to expand...
Somebody will probably trip over it so you'll never find out. And you'll
probably end up getting sued!
 
"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?
Click to expand...
Ooh ooh! Where can I get a little four-step escalator for my living room?
 
In alt.binaries.schematics.electronic,
sci.electronics.cad,
sci.electronics.design,
sci.electronics.misc,
Jim Thompson <thegreatone@example.com> wrote:

If you place a Slinky on an escalator, will it go forever ?:)
Click to expand...
This is misuse of a Slinky. A Slinky should be stretched out with a
transducer at each end and used as a "spring reverb."

...Jim Thompson
Click to expand...
-----
http://mindspring.com/~benbradley
 
On Sat, 6 Mar 2004 15:39:52 -0800, "Tim Wescott"
<tim@wescottnospamdesign.com> wrote:

"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)

...Jim Thompson
[snip]

Ooh ooh! Where can I get a little four-step escalator for my living room?
Click to expand...
I've actually seen a two-platform slinky driver (slinky permanently
attached on each surface), and it just pumps back and forth
incessantly ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?
 
John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> says...

The other interesting part is the longterm stability of the slinky
itself. If it can reach too far, it might wander out on progressive
steps, trip on an edge, and tumble. If it's too short, it may land on
the same step it's on, and die there. I suppose it has to have a step
distance slightly below the tread width and occasionally brush a riser
to apply some longterm centering stability. There are lateral
stability issues, too.

Is a slinky ever longterm stable walking down stairs?
Click to expand...
Good question!

I suspect that curving the stair surface can make it laterally
stable.



--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
have an "impossible" engineering project that only someone like
Doc Brown can solve? My resume is at http://www.guymacon.com/
 
"Mike Rocket J. Squirrel Elliott"
<j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDOT.net> wrote in
message news:CPGdnXeDU8ia2tfdRVn-ug@adelphia.com...
: Paul Burridge wrote:
: > On Sat, 06 Mar 2004 11:35:57 -0700, Jim Thompson
: > <thegreatone@example.com> wrote:
: >
: >>On Sat, 6 Mar 2004 13:23:31 -0500, "Bill Garber"
: >><willy46pa@comcast.net> wrote:
: >>
: >>>"Philip A. Marshall" <philmarshall@hotmail.com> wrote in
message
: >>>news:rn5k40pmtirls5ftdpd5khu3j509pa0o64@4ax.com...
: >>>: On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
: >>>: <thegreatone@example.com> wrote:
: >>>:
: >>>: >If you place a Slinky on an escalator, will it go forever
?:)
: >>>:
: >>>: not if the escalator is going down :)
: >>>:
: >>>: or if it's going up too quickly
: >>>
: >>>Or turned off, or moving too slowly.
: >>>
: >>>Lots of variable left out Jim. I sort of
: >>>remember you complaining about people doing
: >>>that with your classroom tests here. 8o)
: >>>
: >>
: >>It's a question "for discussion" ;-)
: >
: >
: > More of a "thought-provoking metaphysical conundrum" IMV. :)
:
: Hang on -- a conundrum is a riddle in which a fanciful question
is
: answered by a pun. Like:
:
: "How is a cat's tail like a long road?"
:
: "Because they are both `fur' to the end."
:
: We got the fanciful question part. Now we need the punnish
answer.
: /Then/ we'll have a conundrum.

Jim, can you "spring" into action here before it "escalates",
or will you try to "slink" out of it. LMAO! (as I duck and run)

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4SPAM6pa@comXcast.net
Remove - SPAM and X to contact me



---
This email ain't infected, dude!

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.593 / Virus Database: 376 - Release Date: 2/20/04
 
"Jim Thompson" <thegreatone@example.com> wrote in message
news:lgpk40p0muglse13ub00fgd4uhgvnfc3ec@4ax.com...
: On Sat, 6 Mar 2004 15:39:52 -0800, "Tim Wescott"
: <tim@wescottnospamdesign.com> wrote:
: >
: >"Jim Thompson" <thegreatone@example.com> wrote in message
: >news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
: >> If you place a Slinky on an escalator, will it go forever
?:)
: >> ...Jim Thompson
: [snip]
: >
: >Ooh ooh! Where can I get a little four-step escalator for my
living room?
:
: I've actually seen a two-platform slinky driver (slinky
permanently
: attached on each surface), and it just pumps back and forth
: incessantly ;-)
:
: ...Jim Thompson

Jim,

I have the correct response to your question as it
was notibly worded and undiscovered by all to this
point. The answer is NO!, it can't, as it was only
"placed" onto the escalator it will eventually reach
the top or the bottom depending on which escalator
it is "placed" onto. Now what do I get? Heh Heh!
You never mentioned that the Slinky was set to motion.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4SPAM6pa@comXcast.net
Remove - SPAM and X to contact me



---
This email ain't infected, dude!

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.593 / Virus Database: 376 - Release Date: 2/20/04
 
On Sat, 6 Mar 2004 22:18:21 -0500, "Bill Garber"
<willy46pa@comcast.net> wrote:

[snip]
Jim, can you "spring" into action here before it "escalates",
or will you try to "slink" out of it. LMAO! (as I duck and run)

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4SPAM6pa@comXcast.net
Remove - SPAM and X to contact me
Click to expand...
I'll do my best !-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?
 
In
alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.design,sci.electronics.misc,
"Tim Wescott" <tim@wescottnospamdesign.com> wrote:

"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?

Ooh ooh! Where can I get a little four-step escalator for my living room?
Click to expand...
Right here:

http://www.stairmaster.com/commercial/products/stairclimbers/stepmills/stepmill7000pt/index.html

But I think the steps only go down, you may have to modify it so
the steps go up, to keep your Slinky in tip-top stair-descending
shape.
-----
http://mindspring.com/~benbradley
 
"Tim Wescott" <tim@wescottnospamdesign.com> wrote in message
news:104ko9so6r6hhdd@corp.supernews.com...
"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Will you still need me, will you still feed me, when I'm sixty-four?

Ooh ooh! Where can I get a little four-step escalator for my living room?
Click to expand...
The hard part is digging out the big basement to store all the steps.
 
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:7c584d27.0403061516.3674dc9f@posting.google.com...
John Fields <jfields@austininstruments.com> wrote in message
news:<otak40tnpcvg735brln36aqprtdnpaiju7@4ax.com>...
On Sat, 06 Mar 2004 11:47:47 -0800, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 06 Mar 2004 12:52:27 -0600, John Fields
jfields@austininstruments.com> Gave us:

On Sat, 06 Mar 2004 18:22:59 GMT, Philip A. Marshall
philmarshall@hotmail.com> wrote:

On Sat, 06 Mar 2004 11:15:35 -0700, Jim Thompson
thegreatone@example.com> wrote:

If you place a Slinky on an escalator, will it go forever ?:)


not if the escalator is going down :)

or if it's going up too quickly

---
Or if it's going up too slowly, so we'd need to servo the escalator to
the slinky's period.

Start at the top with the escalator off. When the slinky reaches
the bottom (near it), turn the escalator on, bring the slinky back to
the top, and then turn it off again. No servo, just an on off button
"server". Hehehe...

That's still a servo, hehehe...

Yep. A very crude bang-bang controller. In principle you should be
able to tune the speed of the elevator to keep the Slinky in more or
less the same place - it is effectively an oscillator, so that analogy
would be with a phase-locked loop rather than a simple analog control
loop.

In any event it begs the question of how you reliably detect where the
Slinky is. I suppose it is optically dense enough that a
photo-detector would work - I'd think in terms of two bright, fairly
narrow beam leds, one on either side of the escalator, and two pairs
of photo-dectors, about twice the Slinky diameter apart, on either
side of the escalator, flanking the leds.

----------
There is exactly the right escalator at Gdansk airport, it stops 1 run + 7
Click to expand...
steps over when someone gets on at the bottom so provided the slinky can
move 7 steps in this time period it should run forever (all other variables
sorted). It's sad what one does when waiting for a plane.

Who is going to try it?
 
"Jim Thompson" <thegreatone@example.com> wrote in message
news:l85k4012sak0bb8qt0il8issb32dkf0p6t@4ax.com...
If you place a Slinky on an escalator, will it go forever ?:)
Click to expand...
Only if you match the escalator speed dynamically to the slinky, and
dynamically adjust the stair tread depth to stop the slinky slowly
edging further out or in and stalling, plus add air jets each side to
stop it bumping into side walls. So... its possible.

Regards, NT
 
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