Question

Two identical particles of charge q each are connected by a massless spring of force constant k. They are placed over a smooth horizontal surface. They are released when the separation between them is r and spring is unstretched. If maximum extension of the spring is r, the value of k is (neglect gravitational effect)

Answer 1

work energy theorem
mech energy conserved(no internal conservative force)
q*q/4*pie*E*r=kr^2/2
you may find k.........