The Newton-Euler model is described in terms of particles.  Each
particle is considered as a point that has an associated mass
 .  Forces may act on any particle.  The motion of a rigid body,
covered in Section 13.3.3, is actually determined by
modeling the body as a collection of particles that are stuck
together.  Therefore, it is helpful to first understand how particles
behave.
.  Forces may act on any particle.  The motion of a rigid body,
covered in Section 13.3.3, is actually determined by
modeling the body as a collection of particles that are stuck
together.  Therefore, it is helpful to first understand how particles
behave.