Ball balancing on air flow

Recently, someone at my university told me about a case of experiments connected to aerodynamics* that they occasionally use for demonstrations and outreach. Obviously, I asked if I might possibly borrow the case, and fast forward: my dad and I spent a whole weekend playing.

I’m gonna go through all the experiments over the next couple of posts, so let’s get started!

The first experiment has a slight ring of the balls balancing on water jets. I’m a little torn on which one I like better. The experiment below looks a little more like magic, because the air jet is invisible. But the balls are balancing on water jets. Water! Tough choice!


Ball balancing on air jet

So this is what happens: The ball sits on the edge of the jet. The jet speeds up where it flows around the ball, and according to Bernoulli the pressure sinks and the ball is being pushed into the jet by the air pressure from outside the jet.

In the movie below you see how the ball can balance quite stably if left alone in the position it finds for itself, and how it reacts to the air flow being disturbed.

*This is the case: Experimentierbox Flug und Fliegen. This is not an affiliate link, they don’t know me and I don’t get anything for linking.

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