Ifwithseparation of variables gives
Ifatwe can integrate this:
This motion is only defined forWhengoes to infinity. Of course in any physical system the model will break down before this time. In general the motion is defined as terminating if it is represented by a solution of the motion which is undefined at some finite time.
which can be arranged to give
The system reachesatNo motion satisfying (1) is possible after this time and the motion terminates there.