At 12:32 PM 2/18/5, Robin van Spaandonk wrote: >In reply to Horace Heffner's message of Wed, 16 Feb 2005 01:13:26 -0900: >Hi, >[snip] >>The velocity of collision of two bodies of mass and radius M, R, m and r >>respectivley, is gravitationally bounded (on the low side) by >> >> V = (2 G M/(R+r))^0.5 + (2 G m/(R+r))^0.5. >> >>In the case of a body docking with the space station both M and m are very >>small. In the case of planet or moon sized collisions, M and m are large, >>so the total kinetic energy is large and thus V is large. >[snip] >Here you assume the low side initial velocity is zero, however it could >also be negative (through interaction of one or both with a third body). >>From a different point of view, the formula above assume a starting point >>infinitely far away, however the starting point may be close by, >>resulting in no opportunity to pick up speed.
That is true. A three body interaction close to Iapidus could produce a lower energy collision. The third body might carry away much of the momentum, as viewed from Iapidus' inertial frame, or the momentum and energy of objects moving in opposed directions could be spent in a head-on collision close to Iapidus, spraying it with debris. Regards, Horace Heffner
