In my world a human being gained powers through a special stone. He never showed it to anyone and does not even want it. At some point in the story he is obliged to cooperate with scientists who want understand his power and acquire knowledge of it.
His power is like "the force" in star wars: the stone converts his thoughts into actions, he can manipulate local gravity as he wants, but with concentration limitations (usually he can't do more than 2 things at the same time without some loss). His body is normal like that of an average human, so he can hurt himself. Usually he needs to see what he is doing because it's too risky to use the power blindly. The power of his actions has no limitation, he can lift a whole mountain or just a pen, but the quantity of actions is, he can lift a mountain but can't sustain four pens at each corner of a room.
Scientists perceived these limitations and want to do tests to acquire knowledge, find ways to control him, etc. What kind of tests would they do?
I'm thinking in general areas, not just physics, which is the obvious one. Biology, psychology and so on.