Contents

44 3 Basics of Geophysical Fluid DynamicsFig. 3.12 Appearance of straight path (white line) of an object (ball) for an observer on a rotatingturntable. The inner end of the white line shows the starting position of the object. The SciLabscript “Straight Path.sce” in the folder “Miscellaneous/Coriolis Force” of the CD-ROM producesan animation3.12.2 The Centripetal Force and the Centrifugal ForceConsider an object attached to the end of a rope and spinning around with a rotatingturntable. In the f xed coordinate system, the object’s path is a circle (Fig. 3.13) andthe force that deflect the object from a straight path is called the centripetal force.This force is directed toward the centre of rotation (parallel to the rope) and, hence,Fig. 3.13 Left panel In the f xed frame of reference, an object attached to a rope and rotatingat the same rate as the turntable experiences only the centripetal force. Right panel: The objectappears stationary in the rotating frame of reference, which implies a balance between the centripetalforce and the centrifugal force. The SciLab script “Centripetal Force.sce” in the folder“Miscellaneous/Coriolis Force” of the CD-ROM produces an animation