[jandrese]

I guess it comes down to the details of your fictional FTL drive. A lot of times normal space momentum is not maintained in FTL, and gaining normal space momentum requires conventional rockets where delta-V is hugely expensive in terms of mass and volume.

[rbanffy]

I don't remember any sci-fi story with a jump drive mentioning this issue. There is one book, IIRC, Cassini Division, where a devastating attack is carried out by dragging one end of a wormhole at high speed to capture icy asteroids and launch them at a high velocity from the other end against a planetary target.