fluid mechanics vs mechanics

fluid mechanics and mechanics both are nouns.

Word	Noun	Adjective	Verb	Adverb
fluid mechanics	Yes	No	No	No
mechanics	Yes	No	No	No

As nouns, mechanics is a hypernym of fluid mechanics; that is, mechanics is a word with a broader meaning than fluid mechanics:

fluid mechanics: study of the mechanics of fluids
mechanics: the branch of physics concerned with the motion of bodies in a frame of reference

fluid mechanics (noun)	mechanics (noun)
study of the mechanics of fluids	the technical aspects of doing something
	the branch of physics concerned with the motion of bodies in a frame of reference