Q. A system consisting of two masses connected by a massless rod lies along the $x$-axis. A $0.4\ kg$ mass is at a distance $x = 2m$ while a $0.6\ kg$ mass is at a distance $x = 7m$. The $x$- coordinate of the centre of mass is

A) $5m$
B) $3.5m$
C) $4.5\ m$
D) $4m$
Explanation

(a) $x_{cm} = \frac{m_{1}x_{1} + m_{2}x_{2}}{m_{1} + m_{2}} = \frac{0.4 \times 2 + 0.6 \times 7}{0.4 + 0.6} = 5m$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.