# Why do stationary pools of water not rotate?

During the coriolis effect, does gravitational potential energy get converted into rotational energy? Why do stationary pools of water not rotate?

A careful look into the Coriolis force formula ( ${\bf F}_{\rm C}=-m{\bf\Omega}\times {\bf v}$) can answer your two questions:

1. Coriolis force is zero when ${\bf v}={\bf 0}$, that's why stationary pools do not rotate.

2. Coriolis force is always normal to velocity vector (since it results from a cross product), so it doesn't affect kinetic nor potential energy, it just changes the direction of motion.

The water in the pool does not rotate because you are in the pool reference frame.

Rotate a glass with water and get into the glass reference frame. The water will be sill.

From another reference fame (disconnected from the Earth), the pool moves together with the Earth and the level in the pool is established due to two forces - gravitational and centrifugal.

• You must write more – sofky Mar 30 '17 at 18:56