# Simple rotational dynamics

I have a car moving in straight line with certain time-varying acceleration and there is another car moving in a curvilinear way along some curved path with some time-varying acceleration. The inertial reference frame is say fixed at some point in space. The relative velocity and acceleration at any instant is calculated.

Why is the relative velocity of the car moving in curved path from the point of view of the car moving in straightline, different from the relative velocity of the car moving in straightline from the point of view of the car moving in the curved path? I know that in mathematical formulation this will involve the instantaneous angular velocity of the car following the curved path. But that is not very intuitive to me. Is there any way I can understand this situation clearly and more intuitively,i.e., Visualize it.  • This belongs in Physics.SE, where you will find a few dozen duplicates of this question. – Carl Witthoft Jan 6 '16 at 12:54