The Coriolis effect is an effect that derives from the Coriolis
force.
Assuming there is an object of mass, standing on a spinning surface
and trying to reach from one point of the surface to another point, and
therefore have axial velocity – cannot go in a straight direction – instead it
moves in curve, this phenomenon explained by Coriolis force.
The
effect can be seen in our daily life, for example: the way of the currents
around the world derive from the Coriolis force that cause by the spinning of
Earth, same with the wind directions. Those examples can be explained easily
thanks to this video:
Now to the question: assuming that there are two friends, sitting on
a carrousel that spins clockwise from both sides, one of them holding a ball
and want to deliver it to the other friend.
In which direction shall that friend throw the ball?