Two particles of masses `m_(1)` and `m_(2)` initially at rest a infinite distance from each other, move under the action of mutual gravitational pull. Show that at any instant therir relative velocity of approach is `sqrt(2G(m_(1)+m_(2))//R)` where `R` is their separation at that instant.

Options

A. `sqrt((G(m_(1)+m_(2)))/(r))`
B. `sqrt((2G(m_(1)+m_(2)))/(r))`
C. `sqrt((Gm_(1)m_(2))/((m_(1)+m_(2))r))`
D. `sqrt((G(m_(1)+m_(2)))/(2r))`

Answer

B