A square plate of edge d and a circular disc of diameter d are placed touching each other at the midpoint of an edge of the plate as shown in figure (9-Q2).Locate the centre of mass of the combination,assuming same mass per unit area for the two plates.
Let m be the mass per unit area.
∴ Mass of the square plate=M1=d2m
Mass of the circular disc=M2=πd24 m
Let the centre of the circular disc be the origin of the system,
∴ x1=d,y1=0
x2=d,y2=0
∴ Position of centre of mass=(d2md+π(d24)m×0d2m+π(d24)m,0+0m1+m2)
=(d3md2m(1+π4),0)
=(4dπ+4,0)
The new centre of mass is 4dπ+4 right to the centre of circular disc.