Question

Two identical particles move towards each other with velocity $2v$ and $v$ respectively. The velocity of centre of mass is

• A. $v$
• B. $v/3$
• C. $v/2$
• D. zero

Answer 1

Answer: (C)

$v_c=\frac{m_1{v}_1+m_2{v}_2}{m_1+m_2}$
or $v_c=\frac{m(2v)+m(-v)}{m+m}=\frac{v}{2}$