Coriolis' force acts upon moving objects in a rotating system and attempts to change their locus. As the cycles of the rotating table and the pendulum become closer, the effect of Coriolis' force becomes clear, and the locus of the pendulum gradually becomes rounder. This picture shows the locus of the pendulum with a period 2/3 of the revolution cycle. This does not look like a linear motion at all. But it does move back and forth linearly if you look at from the out side of the rotating table. Looking while rotating makes the phenomenon look totally diffrent.