Two particles of masses `p` and `q (p gt q)` are separated by a distance `d`. The shift in the centre of mass when the two particles are interchanged is

Options

A. `d(p+q)//(p-q)`
B. `d(p-q)//(p+q)`
C. `dp//(p-q)`
D. `dq//(p-q)`

Answer

B

Explanation

`x_(cm) = (m_(2)d)/(m_(1)+m_2) = (pd)/(p+q)`
` x_(cm)^(1) = (m_(1)d)/(m_(1)+m_(2)) = (qd)/(p+q) ," shift " = x_(cm)^(1) ~ x_(cm)`