# Here_s an interesting thing. The juggli

Here's an interesting thing. The juggling prop called a diabolo has the same curvature as a torus. I discovered this while crocheting. I was making a torus and before sewing the edges together I realised that the surface would sit quite happily (no crumpling) in either pose. Like popping a rubber hemisphere in and out.

The torus/diabolo has negative curvature in the middle (the hyperboloid bit) and positive curvature elsewhere, with two circles of zero curvature in between. Presumably the popping only affects the region of positive curvature.

There's one other zero-energy configuration, not shown, where one side is popped out but not the other.

Has this sort of thing been studied? What other curved surfaces have multiple zero-energy configurations?

The torus/diabolo has negative curvature in the middle (the hyperboloid bit) and positive curvature elsewhere, with two circles of zero curvature in between. Presumably the popping only affects the region of positive curvature.

There's one other zero-energy configuration, not shown, where one side is popped out but not the other.

Has this sort of thing been studied? What other curved surfaces have multiple zero-energy configurations?

Shared with: Public, Paul Fisher

+1'd by: JF Peter sen, Bob Nystrom, Ángel Linares García, Roice Nelson, Whitt Whitton, Jose López Prada, Dmitry Shintyakov

Reshared by: Douglas Perrin, Jose López Prada

*This post was originally on Google+*

Hyperbola from Sticks | English | Straight Line to Curve

but I think you're talking about something else. Are there instructions to make it somewhere?

For instance, if you could force the train station roof in the picture to flex, you could switch it so that the “up” and ”down” corners were in the opposite configuration, with all the straight lines still remaining straight (after the flexing process was complete, that is).