Question

derive an expression of centre of mass of two particles

Answer 1

Expression of center of mass of a two particle system in easy way. Consider a system consisting of two point masses m1 and m2, whose position vectors at a time t with reference to the origin O of the inertial frame are respectively. It is the point where the total external force is supposed to act. If i.e., the mid- 

Answer 2

Centre Of Mass:
COM of a body is a point where the entire mass of the body can be supposed to be concentrated.
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