"That's good."

He finishes suiting up, tests the communication things, and heads out of the shuttle. "I'd like some things I can try throwing around - preferably large and obvious without being so heavy a civilian couldn't budge them - about, oh, a hundred feet from where I'm anchored to start?"

Cam stick an anchor deep into the moon and tethers it to Sasuke's ankle and provides him some traditional wooden barrels.

It takes him a bit of mental fiddling, but soon he's sending barrels flying to and from points - 

And then he switches places with one, his tether left behind.

- going too fast to re-tether?

No; he's exactly at his previous velocity. He appears to have teleported.

Cam re-tethers him and belatedly makes a headset so he can talk into the spacesuit helmet and vice-versa. "Keen!"

"Wasn't expecting that... I might try poking it, just to warn you."

"It doesn't seem to accelerate you or anything, and you did bring the suit, so that's probably all right."

"Yeah. Can I have some things of different sizes and masses to practice switching with?"

"Do you want them to look obviously different or should I just fill assorted barrels with different stuff?"

"I think I'd like to test if this gives me a sense of masses, so the latter."

Barrels of feathers! Barrels of tungsten! Barrels of water! Little ones and big ones.

He can only switch with things three times before the ability apparently goes on cool-down, but his ability returns within a few minutes (which he spends playing around with other senses). Switching with different volumes doesn't change how much chakra it takes, but he reports that he can feel what mass and velocity something is and that things that are farther from his own mass cost more chakra.

"Huh, it's distance from your own mass? By like, factor or absolute amount - is something that masses half as much as you like something twice as massive or like something only half again as massive -"

"I probably would need actual measurements to figure that out, this sense doesn't come with convenient units."

Cam makes appropriately massed barrels!

He figures out that half as much mass does cost him the same as twice as much mass, but twice as much mass isn't cleanly half the chakra of four times as much mass, which means some kind of equation's at work. He hates equations.

"I'll make the computer do it, just report all the data points and we'll have a graph."

"Would a unit-less scale where I assign some arbitrary amount of chakra as 'one' work?"

"Sure."

He designates 'switching with an identical mass' as 'one.'

The function seems to be quadratic-ish in shape. Four times is significantly more than twice, eight times significantly more than four. He identifies 'switching with an identical mass' as fairly low chakra, so he can manage some of the extremes, but he can't switch past 'twenty times/ one twentieth' his own mass. He's pretty sure that's a 'yet'. 

Cam graphs it and presents him with the derived equation.

"Huh. So I'm probably going to have a lot more than conceptual trouble swapping with an equal volume of air."

"Maybe it'll ever make sense to compress some air with gravity powers first."

"Was more thinking for tactical use, or if I can't find convenient objects around my target."

"Though if I'm fighting someone I may be able to swap with them."