Slinky

[Moontanman]

Is this an effect that can be explained? The bottom of the slinky always hovers until the top reaches it...

 

https://lh6.googleusercontent.com/-caaugfzCvlg/U8602uHWxVI/AAAAAAAAFuM/pgAkBL9NzWM/w280-h314-no/dada.jpg

[moth]

Shame on you

you should read Swans on Tea

[pzkpfw]

The spring is contracting when released from the top.

 

Presumably the contraction balances nicely with the overall fall (the centre of mass of the overall spring is going downwards).

 

When fully contracted, the continued fall becomes obvious.

 

Since the stretch of the spring is caused by gravity, it's seems no surprise (to me) that the contraction balances like that.

 

 

 

Edit: Typed too slow again. Did I get it anywhere near right?

Edited July 23, 2014 by pzkpfw

[Moontanman]

SwansonT got me again!

[MonDie]

I've got a better question. Why doesn't a hoola-hoop fall to the ground if it's spinning around somebody's waist? No upward force is applied to it, so shouldn't it fall?

 

... or is there? The surface isn't perfectly vertical. Spin a plastic bottle-ring around your finger, then try to spin it around a cylindrical writing utensil.

Edited July 25, 2014 by MonDie

[swansont]

I've got a better question. Why doesn't a hoola-hoop fall to the ground if it's spinning around somebody's waist? No upward force is applied to it, so shouldn't it fall?

 

... or is there? The surface isn't perfectly vertical. Spin a plastic bottle-ring around your finger, then try to spin it around a cylindrical writing utensil.

 

There is an upward force, as you suspect. It's subtle because the hoop is curved.