Four particles A, B, C and D having masses m, 2m, 3m and 4m respectively are placed in order at the corners of a square of side a. Locate the centre of mass
Take the axes as shown in figure. The coordinates of the four particles are as follows:
Hence, the coordinates of the centre of mass of the four-particle system are
x = m.0 + 2ma + 3ma + 4m.0m + 2m + 3m + 4m = a2y = m.0 + 2m.0 + 3ma + 4mam + 2m + 3m + 4m = 7a10
The centre of mass is at (a2,7a10).