Maybe you’ve seen one of these “floating” tables on the internet. They look crazy because at first glance, it seems like the table is standing up on strings instead of on solid legs. Which is impossible, right? I mean, you can pull strings to make something happen, but everyone agrees that pushing on a string is futile. So why doesn’t it collapse?

Of course it’s not magic, it’s just physics. This structure is an example of a tensegrity system—a term coined by Buckminster Fuller—which means that its integrity, or stability, comes from balancing elements under tension.

Here’s one that I made out Lego blocks Yes, I can even put a book on top of it.

If you look closely and think about it, you’ll start to see what’s going on here. Whereas an ordinary table stays up because the tabletop pushes down with the weight of gravity on some rigid legs, this one is held together by a balance of forces pulling in different directions. Those strings on the left are actually pulling up!

Let's figure out exactly how this magic table works, then I’ll show you how to make one of your own to astound and amaze your shelter-in-place mates.

Two Conditions of Equilibrium

If an object is at rest (meaning that it’s not accelerating), we say it’s in a state of equilibrium. This means that the following two conditions must be true: