Mechanics is the oldest physical science that deals with both stationary and moving bodies under the influence of forces.
The branch of mechanics that deals with bodies at rest is called Statics, while the branch deals with bodies in motion is called Dynamics.
Kinematics and kinetics together form the field of Dynamics.
Collectively, the study of statics and dynamics is called classical mechanics. Classical mechanics treats the motion of bodies of ordinary size that moves at speeds that are small compared to the speed of light. It includes the special case of statics (Equilibrium) in which a body is at rest or moves in a straight line with constant speed, as well as the special case in which a body is sufficiently rigid or stiff that its deformation has no effects on its motion.
The great importance of Newton’s contributions to mechanics is evidenced by the fact that classical mechanics is often called Newtonian Mechanics.
The fundamentals principles of Newtonian Mechanics may be used to study the conditions of rest or motion of rigid bodies of ordinary size that move at ordinary speeds.
The theories of relativity and quantum mechanics show that Newtonian Mechanics is inexact when speeds approach the speed of light or when the motion of subatomic particles is considered.