Newton's second law
In an inertial frame, with the momentum; the net force can depend only on and at the current time.
In an inertial frame,
where is the momentum of the particle and is the net force acting on the particle.
The momentum is defined to be , where is the inertial mass.
The mass is an additional property of particles. It could change with time, but we generally assume it is constant unless otherwise specified.
The force depends on the interaction, but can only depend on and at the current time.
Determinism
Newton’s second law is a second order ODE for . Given and at for all particles, Newton’s equations uniquely determine for all future times.
Scope of validity
Newtonian mechanics has been superceded by quantum mechanics (small scale) and relativity (high speed), but remains an excellent approximation for much of the universe.
Related
Stated in
- Law 2.1 (Newton's 2nd Law)§2.1 Newton’s Second Law