Newton-II 3.0 for Mac can be downloaded from our website for free. The actual developer of this software for Mac is University Wuerzburg - Germany. The software is categorized as Education Tools.
From the developer:
Newton-II is a program for solving mechanical equations of motions numerically. The equations can be parameterized for interactive investigations of the motions. The according solutions are displayed immediately in a diagram.
The differential equations (DEQs) are programmed to calculate the time dependence of the velocitiy v(t) of a point of mass from the given acceleration a. Then the location s(t) is calculated from v(t).
You may want to check out more Mac applications, such as sciatrope, NWB or MicroWorlds EX, which might be related to Newton-II.