In the picture, the black ball is moving in a straight line in the inertial frame of reference (upper part of the picture). However, the observer (red dot) who is standing in the rotating/non-inertial frame of reference (lower part of the picture) sees the object as following a curved path. This is because the observer is also rotating, and the Coriolis and centrifugal forces are acting on the object.
#Physics #Coriolisforce #centrifugalforce