Quote:
Originally Posted by sjastro
You are not comparing apples to apples
......
The energy supplied for converting a circular orbit to parabolic orbit is due to external non conservative forces. The KE+PE = constant rule no longer applies. This is contrary to the effects of gravity on the inertia of masses in the absence of external forces on which the Universe is modelled on.
Regards
Steven
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OK, now I think I see where the difference is (and I hope it is more clear to others as well).
Summa summarum:
Our little system is not closed (it is open to external influence).
Universe is a closed system.
Thanks..