system of particles.docx - In the earlier chapters we...

In the earlier chapters we primarily considered the motion of a single particle. (A particle
is represented as a point mass. It has practically no size.) We applied the results of our
study even to the motion of bodies of finite size, assuming that motion of such bodies
can be described in terms of the motion of a particle.
Any real body which we encounter in daily life has a finite size. In dealing with the motion
of extended bodies (bodies of finite size) often the idealised model of a particle is
inadequate. In this chapter we shall try to go beyond this inadequacy. We shall attempt
to build an understanding of the motion of extended bodies. An extended body, in the
first place, is a system of particles. We shall begin with the consideration of motion of the
system as a whole. The centre of mass of a system of particles will be a key concept
here. We shall discuss the motion of the centre of mass of a system of particles and
usefulness of this concept in understanding the motion of extended bodies.