Four particles of masses 1kg, 2kg, 3kg and 4kg are placed at the four vertices A, B, C and D of a square of side 1m. Find the position of centre of mass of the particles. Assume that D is situated at the origin.

Explanation

A suitable choice of axis will be through the sides of the square as shown. Consider `1kg` at origin. Position coordinates of respective masses are shown in figure.

`X=(1xx0+2xxa+3xxa+4xx0)/(10)=(a)/(2)`
`Y=(1xx0+2xx0+3xxa+4xxa)/(10)=(7)/(10)a`
`Z=0`
Coordinates of centrre of mass of the system are `((a)/(2),(7)/(10)a,0)`