Where r is the position vector of a parcel in the rotating frame,Ω is the
rotation vector of the rotating frame of reference, and Ω × r is the vector
product of Ω and r. This is just a generalization (to vectors) of the trans-
formation used in to express the absolute velocity in terms of the
relative velocity in our radial in flow experiment. As we shall now go on to
show, is a special case of a general ‘rule’ for transforming the rate of change of vectors between frames, which we now derive. Consider Fig.6.9. In the rotating frame, any vector A may be written