Does mechanics include astrophysics and atomic/molecular physics?

Question

And what's relationship between mechanics and particle physics, parallel or inclusion?

Answer 1

Yes or you could at least say that they overlap.

Mechanics is a branch of physics dealing with forces and displacements (effects on matter). Mechanics has two branches -- classical and quantum mechanics. The former covers a lot of astrophysics and the later definitely includes atomic theory and particle physics.

Molecular physics is getting into chemistry. The mechanical physics applied to anything more than simple atoms get extremely complex - although computer can model them. Typically, folks use chemical 'rules' for how atoms combine rather than try using physical forces used in mechanics.

Astrophysics uses (mainly) classical mechanics applied to large scale objects. However, recent work on stars, blackholes, and the big bang get heavily into atomic theory.

In practice the lines between these blur extremely heavily. Mechanics used to just be the study of objects and motion and mechanics is now often used to refer to mechanical engineering which includes stresses, movement, physics, etc. on physical structures, vehicles, etc. Pure mechanics as a science are now such basic requirements of nearly all other disciplines that it is hard to treat it as its own discipline.

Answer 2

A course on mechanics usually involves the study several (but not necessarily all) of the following concepts.
Force
Torque
Linear Momentum
Angular Momentum
Kinetic and Potential Energy
Harmonic Oscillators
Stress
Strain

Answer 3

No. Astrophysics can be a college major in itself. Atomic/molecular physics is a seperate as well.