In these next postings, what we try to do, we extend the usual standard classical models. In particular, we ape the notion of a coordinate acceleration. That which is equivalent to the difference between the proper acceleration and the acceleration in a frame in which a particle/entity is undergoing constant acceleration. The link to this rather tenous example has been provided above.
Imagine that the force/acceleration exerted by a particle M^ (M hat) onto another particle U (mu) changes as M^ approaches U.
In the next frame, imagine that M^ is as a result of the breakdown of a much larger particle. That M^ is the difference between the larger mass M1 and the smaller mass M*.
