Physical science was the collection of natural sciences which studied non-living systems.
In 2364, Wesley Crusher was taking a physical sciences class taught by Doctor Channing, in which they discussed the possibility of forcing dilithium into even more useful crystals. (TNG: "Lonely Among Us")
In the Doctor's Family Program Beta-Rho holoprogram, The Doctor's "son," Jeffrey, was considered "extremely bright," so much, in fact, that he was taking the "accelerated physical sciences program" at his school. (VOY: "Real Life")
In one possible dialogue for "Man Of The People", Jeffrey Fratis was part of the physical sciences department.