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jwsea55 said: "Is this still a correct statement when you lay the slinky on its side (Xing out old slinkies will want to flop on their ends)? "

All of the examples I talked about pretty much presume that the axis of the slinky, which is vertical when the slinky is suspended in the video, remains vertical and straight at all times. A real slinky gets its extension/compression spring constant and its torsional spring constant from the nature of the material making up the coils.

Bending the slinky so that its axis is not a straight line, which is what I think you are suggesting, would be a demonstration of a degree of freedom which is not taken into account whatever in my description. Such bending introduces additional ways in which the slinky can interact with a gravitational field or store energy by changing shape.

If you lay the slinky on its side on a horizontal surface such that the axis is straight, and ignoring friction with the surface, the slinky should seek out its neutral position of minimal energy. For a real slinky, this may in fact be where the sides of adjacent coils are touching. There would be no freedom to compress the slinky any further, barring deformation of the coils.

Without friction with the surface, the slinky would exhibit a spring constant describing the amount of force required to separate the coils a particular distance, the distance being proportional to the force.

Sitting on its side, the slinky, though nominally of circular shaped coils, would undergo a very slight deviation from that circular shape due to gravity, similar to the non-uniform extension that I previously described.

Each circular coil of the slinky is supported at a point on the bottom of the coil. This section of each coil supports the entire coil. The parts of the coil halfway from the point of contact to the upper edge of the coil will be supporting only the upper half of the coil. Each coil will then VERY SLIGHTLY (due to the stiffness of the coil) change shape to reflect the load on it. To a first approximation, the circular coil will become slightly oval due to this loading. I think the curvature at the bottom of the coil will be less than the curvature at the top but of this I'm not certain.

Did I understand your question?

Thanks for the clarification. I was thinking that was what you meant but there just wasn't the reference to the necessity 'verticality'.

Sounds like you could teach half a year's physics class on thing. It really is one amazing device for storing and releasing energy.

I am sure I am not the only one who appreciates your time and thoughts! This has been a very entertaining and informative thread.

This thread exhibits one of the reasons why FR is a unique website. ... What an interesting discussion this has been!