•Particle: A very small amount of matter which may be assumed to occupy a single point in space. Particle having a[n mass but [his/its] size measure can be disregarded, so that geometry of object will not be got mixed up with [by] a problem analysis
•Rigid body: A combination of a large number of particles occupying fixed position with respect to each other. Rigid body combination [of] a number of which particle all particle be at a[n distance remain to to one with other;dissimilar
