Question

Two bodies of masses 10 kg and 20 kg are located in x - y plane at (0, 1) and (1.0). The position
of their centre of mass is
1) (2/3, 1/3)
2) (1/3, 2/3)
3) (2, 1)
4) (1/3, 4/3)
​

Answer 1

body A  has mass of 1 kg  and location (1,2)

body B has mass of 2kg and location (-1,3)

mcxc = m1x1 + m2x2

(1+2) xc = (1*1) + (2*-1)

xc  = -1/3

similarly  

mc yc = m1 y1 + m2 y2

(1=2) yc = (1*2)+(2*3)

yc= 8/3

hence the co-ordinates of the center of mass are ( -1/3 , 8/3)