Coriolis Force

A ball sliding on a turntable follows a straight-line trajectory. The force acting on the object in this inertial frame equals the product of mass and acceleration.

When the turntable starts rotating counterclockwise, the sliding ball's trajectory changes. The equation of motion in this non-inertial frame is modified to include the particle's acceleration in the rotating reference frame.

Fictitious forces, including Coriolis and centrifugal forces, act additionally in a rotating frame modifying the equation of motion.

The Coriolis force is proportional to the cross-product of the rotating frame's angular velocity and the object's velocity.

The cross-product right-hand rule gives the direction of the Coriolis force. Consider the palm of the right hand aligning along the rotating frame's angular velocity, and the fingers curl toward the object's velocity. The thumb points opposite the Coriolis force, as indicated by the negative sign in the Coriolis force expression.

So, a ball in a counterclockwise rotating turntable follows a circular trajectory toward the right. If the table rotates clockwise, the ball deflects toward the left.