Re: Questions for those who really know their physics . . .

Erik Max Francis wrote: 
Mark Fergerson wrote:

OK, we know how and why a Slinky will walk down stairs. And BTW in my childhood I was fortunate enough to have access to a somewhat steep set of stairs almost perfectly "tuned" to the natural step length of a steel Slinky; yes, it made it all the way from a second-story landing to the ground nearly every try.

Now, granted that I'm not quite over the tryptophan near-poisoning from last night, and I metabolize eggnog rather faster than most people, but for the life of me I can't see why this doesn't equate to a special case of the elevator gedankenexperiment in that a Slinky on an escalator can't tell whether it's "falling" down the stairs or the stairs are moving up under it. (Note that a Slinky "falls" down stairs with a constant velocity rather than accelerating)

Ya know, I ought to post that in sci.physics as a quantized version of the gedankenexperiment. I think I will.

Hence modeling it physically certainly ought to be feasible.

Yes. In the middle of an escalator, the steps are all moving with constant velocity. Thus the frame comoving with the steps -- that is, where the steps appear to be at rest -- is an inertial frame. All that's left is "engineering" -- choosing steps that have the right height and depth, and tweaking the escalator motion so that it has the same overall movement upward as the slinky does downward.

Which is probably why nobody's bothered to perform the "experiment." There's really no need to.

Thanks for the reality check Erik, but part two of the original question was:

...how much is the 'tumbling' speed be affected by temperature
(i.e. if I build a desktop escalator with a miniature slinky on it,
could it be preset or would there have to be sensors to detect if the
Slinky is staying near the middle and adjust the speed accordingly)?

My intuition says don't worry about it but I've already indicated how trustworthy my intuition is.


  Mark L. Fergerson

.

Relevant Pages

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