Perpetual Slinkies?

[fennster]

If I was to put a slinky on an esculator, which material is best for the slinky and what speed would the esculator need to be going to acheive perpetual motion?

P.s. which would last the longest the slinky or the esculator?

[IndieSinger]

You wouldn't achieve perpetual motion - nothing lasts forever. You could optimise everything (in a trial-and-error manner) until you were blue in the face, but something would eventually give.

Besides, some little kid is bound to press the Emergency Stop button. 

[Hippy]

The goal of creating a "perpetual motion machine" is that the energy is entirely conserved within a local closed loop, so that you give it shove to start things off and the locl system or machine preserves that energy and keeps going for ever without any other input from outside.

The escalator idea sounds a great trick if you can pull it off, you have to balance the speed of the moving stairs with the natural resonance of the spring slinky. It is fraught with problems because small factors (dirt, breeze etc.) could cause the slinky to veer off sideways or wobble on its eternal search for equilibrium and so affect its speed of action.

[Loosehead]

I think fennster meant how fast would the escaltor have to go so that the slinky never reaches the bottom.

Fennster, beware using terms like purpetual motion. As the others point out it means a system that runs perpetually with no energy input, the impossible dream of generations of scientists.

[magicdice]

escalator steps are a different size to regular steps... i'd suggest having a larger radius than usual for the rings. experiment with a slinky on a stationary escalator, work out what the best material & size for the sliky are and time how long it takes to get to the bottom. then you want the speed of your escalator to be the same as the average speed of your slinky

if you actually do this & get it to work, film it for us!

[acw]

Sounds like an idea for another Honda advert! :-)

[Peter Pedant]

Hi Fennster all good questions get people thinking. Remember that a good theory in science - you have to get more out than you put in (to the theory)

1. Select escalator and slinkie.

2. measure rate at which slinkie descends on a stopped escalator. let us call this rate -x der daaah! in some unit or other. (metric) metres/sec

3. Set escalator to go up at x metres/s and video the result.

In fact my prediction is....an ordinary slinkie is getting its energy from going down (pgh and so on) whereas a slinkie on an escalator is going to get some of its energy from the motion (1/2 mv2) -so it should accelerate. hence the video - I would be interested to se e the result.

[tomd]

Wouldn't the energy being put into the escalator stop it being a perpetual motion machine? It's not going to turn by itself. If you could invent a zero friction bearing you could make perpetual motion.