Water in a rotating sphere

What can you do here
Observe the surface of the liquid when the container remains immobile. Gradually increase the angular velocity of the sphere. What is happening inside the sphere?

Examine how the world around you looks when seen through the thin layer of liquid in the whirling sphere.

How does it work
In a quickly rotating sphere the fluid moves outside and upwards – it is the result of the centrifugal force dominating over the gravity force. The value of centrifugal force depends on the angular velocity of the container – the higher the rotation speed, the greater the centrifugal force, and the farther away from the centre of the sphere the liquid is pushed. At the highest velocity, the water gathers around the sphere’s equator. Stopping the sphere suddenly or slowing it down causes the fluid to go down.
The liquid layer in the sphere works also as a lens. When we look through the lifted fluid, the image we is inverted.

Interesting facts
Due to whirling, we can pre-dry laundry. Whirling milk is a method of skimming it. Processing uranium in fast-whirling centrifuge allows to enrich this element for power or military purposes.