Question
The position co-ordinates of two particles of masses m1 and m2are (x1, y1, z1) and (x2, y2, z2) respectively. Find the coordinates of the centre of mass.
Solution
The position vectors of masses m1 and m2 are respectively,
Let the position coordinates of the centre of mass be (X, Y, Z).
Therefore the position vector of centre of mass is,
Since,
Comparing the coefficients of
, we get
Let the position coordinates of the centre of mass be (X, Y, Z).
Therefore the position vector of centre of mass is,
Since,
Comparing the coefficients of
, we get 
