First of all, I haven't seen After Earth and calling me a layman in physics would already be an exaggeration, I guess. So the following answer might be a bit vague and oversimplified (and physicists might excuse me for saying anything embarassing), but maybe sufficient for a SciFi movie.
A graviton is a hypothetical (i.e. yet to be found/discarded) ...
Gravitons are still purely hypothetical, so any statement about them can be true (or false).
In physics mass and weight are two different things.
Say if your mass is 70kg, then on earth on a scale you would weigh you in at 70kg, however, on the moon (less gravity) your weight will be less.
The crucial difference between mass and weight is what is being ...
If I recall correctly, the Ursa was on the ship for training purposes. It was there for the ship's crew to try and learn more about the creatures and train other rangers to "ghost". Ultimately, when the ship crashed, it escaped.
As for their intended travel plan, I don't think it was ever alluded to, aside from being Cypher's "last voyage". Ultimately they ...
As requested, my comment has become an answer
From what I recall, she was trying to wake him up because he was in danger (in the real world) and got him to snap out of it by making the face which reminded him that she had died which startled him awake.