(a) $x_{cm} = \frac{m_{1}x_{1} + m_{2}x_{2}}{m_{1} + m_{2}} = \frac{0.4 \times 2 + 0.6 \times 7}{0.4 + 0.6} = 5m$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.