Q. A $2\ kg$ body and a $3\ kg$ body are moving along the $x$-axis. At a particular instant the $2\ kg$ body has a velocity of $3\ ms^{- 1}$and the $3\ kg$ body has the velocity of $2\ ms^{- 1}$. The velocity of the centre of mass at that instant is
A) $5\ ms^{- 1}$
B) $1\ ms^{- 1}$
C) 0
D) None of these
Explanation
(d) ${\overrightarrow{v}}_{cm} = \frac{m_{1}{\overrightarrow{v}}_{1} + m_{2}{\overrightarrow{v}}_{2}}{m_{1} + m_{2}} = \frac{2 \times 3 + 3 \times 2}{2 + 3} = \frac{12}{5} = 2.4m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.