This is a cool experiment showing off some liquid droplets on a spherical surface coated with a special compound:

Consider an object starting at rest at the top of a frictionless sphere. The equilibrium at the top is unstable. Any little nudge to one side will cause it to begin sliding down the surface. If the object stays on the surface, the normal force will clearly go to zero when the side become vertical. But will it become zero before that and cause the object to leave the surface?

Let’s watch the cool effect in the video on page 2

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