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)`