Yes, MECHANICS is a Scrabble word!

Letter values in Scrabble US: M 3, E 1, C 3, H 4, A 1, N 1, I 1, C 3, S 1.

Is it a valid word?

MECHANICS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the branch of physics concerned with the motion of bodies in a frame of reference
the technical aspects of doing something
a craftsman skilled in operating machine tools
someone whose occupation is repairing and maintaining automobiles

Also: shop mechanic, automobile mechanic, auto-mechanic, car-mechanic, grease monkey.