Q.
Three bricks each of length $L$ and mass $M$ are arranged as shown from the wall. The distance of the centre of mass of the system from the wall is
A) $L/4$
B) $L/2$
C) $(3/2)L$
D) $(11/12)L$
Explanation
(d) [image:7_image155.png]
From figure, $x_{1} = \frac{L}{2},\ x_{2} = \frac{L}{2} + \frac{L}{2} = L$
$x_{3} = \frac{L}{2} + \frac{L}{4} + \frac{L}{2} = \frac{5L}{4}$
$\therefore X_{CM} = \frac{m_{1}x_{1} + m_{2}x_{2} + m_{3}x_{3}}{m_{1} + m_{2} + m_{3}}$
$= \frac{M \times \frac{L}{2} + M \times L + M \times \frac{5L}{4}}{M + M + M} = \frac{\frac{11}{4}ML}{3M} = \frac{11L}{12}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.