Swapnil Saxena
Last Activity: 13 Years ago
The gravitational potential energy of the a pair of particles is -Gmm/l2
Since there exist three pairs (3 particles constitute three pairs) then the potential energie of system is -3(Gmm/l)
When the side of the cube is increased frm l to 2l then the potential energy of system is -3(Gmm/(2l))
Subtracting final Uf with initial Ui = 3(Gmm/(2l))
Note: If we are bringing the particles away frm each other then we have to supply energy against gravitation so it is definitely +. So no chance for option a,b
So clearly Option (c)