Three particles of mass $m$ each are placed at the three corners of an equilateral triangle of side

Question

Three particles of mass $m$ each are placed at the three corners of an equilateral triangle of side $a$. Find the work which should be done on this system to increase the sides of the triangle to $2a$.

Professor PC Thomas Classes · Answer

Initial $U_i = -\frac{3Gm^2}{a}$. Final $U_f = -\frac{3Gm^2}{2a}$. Work $W = U_f - U_i = \frac{3Gm^2}{2a}$.