Question

Find the centre of mass of a rectangular lamina having sides $8\text{m}$ and $6\text{m}$ as shown in figure. [Take $\text{O}$ as origin]

• A. $(3,4)\text{m}$
• B. $(4,3)\text{m}$
• C. $(3,3)\text{m}$
• D. $(4,4)\text{m}$

Answer 1

The correct option is B $(4,3)\text{m}$

Sides of the rectangular lamina are $l=8\text{m}$ and $b=6\text{m}$.


Co-ordinates of $COM$ of a rectangular lamina having sides $l$ and $b$ is given by $(\frac{l}{2},\frac{b}{2})$

Here, $(x_{COM},y_{COM})=(\frac{l}{2},\frac{b}{2})$
$=(\frac{8}{2},\frac{6}{2})\text{m}$
$=(4,3)\text{m}$
So, position of $COM$ of rectangular lamina is $(4,3)\text{m}$

Alternate:
From symmetricity we can say that the COM will be
at $(x,y)=(\frac{l}{2},\frac{b}{2})=(4,3)$