Question

Two identical particles each of mass m are projected from points A and B on the ground with same initial speed u making an angle $\theta$ as shown in the figure, such that their trajectories are in the same vertical plane. The initial velocity of the centre of mass is

• A. ucos $\theta$
• B. $2u\cos \theta$
• C. usin $\theta$
• D. $2u\sin \theta$

Answer 1

The correct option is C usin $\theta$

$V_{X\left(CM\right)}=\frac{m\left(u\cos \theta \right)+m(-u\cos \theta )}{2m}$

$V_{Y\left(CM\right)}=\frac{m\left(u\sin \theta \right)+m(-u\sin \theta )}{2m}$

$=u\sin \theta$