Portal Question: A or B

File: PEpTH.jpg (33KB, 636x424px) Image search: [Google]

33KB, 636x424px

Reasons for A:
Conservation of momentum and energy in the given reference of frame

Reasons for B:
v - V = v’ argument:
The cube has the velocity we ascribe to the portal if we look at the model from the portal’s frame of reference.
This suggests that the cube has kinetic energy, which means it must conserve that according to the portal.
As the cube’s mass doesn’t change in - or exiting - the portal (I hope) its relativistic speed must be similar to the relativistic speed before entering the portal, thus it appears to be flying away from the portal.

Collapsible corridor argument:
If you chuck a collapsible corridor at a floating kid (so that the kid goes through the collapsible corridor) it will appear as though the kid is flying away from the corridor, despite the opposite being true.

Any other arguments?