>>15437421in a reference frame with only two objects (in this case a portal and a cube) it is not important what moves and what stands still. Both have a "impact velocity" of X.
Now the portal does not touch, block or really interact with the cube... it's "replaces" its position relative to a third observer (us).
We see the cube enter the portal and exit the other.
Its in this not the question who is moving or standing still but how much "speed" is in this frame.
10km/h portal meets a 90km/h cube equals 100km/h cube existing the other portal.
Where is the energy truely come from? I dont know, portals arnt real and if they are out there they do some creasy shit with our current spacetime model.
Heck we dont know if the portal portals "block" gravity. If they block they create a "gravityshadow" or a "gravity mirror" with its own kind of worms to Q&A from. We also know that Spacetime is related to gravity and speed... a falling heavy will gain and gain more speed and age much much slower. Where is the time gone?
