Question

Three particles each of the mass m are placed at the corners of an equilateral triangle of side d and shown in figure. Calculate (a) the potential energy of the system, (b) work done on this system if the side of the triangle is changed from d to 2d.

Answer 1

(a) As in case of two-particle system potential energy is B given by (–Gm₁m₂ /r), so

U = U₁₂ + U₂₃ + U_{31 or}

(b) When d is changed to 2d, 

U_f = –  3gm² /2d

Thus work done in changing in potential energy is given as

W = U_f – U_i = 3gm² / 2d