Force and Energy (Work Done)??? Below please find an equation of attractive force for a particle: F(r) = -Br where a = 7.3 F(x) D Press Esc to exit full screen xi This area is the work done 2X4 1, p= .001. The negative sign indicates that the force is attractive. How much energy is needed to pull two of these particles apart from r = 0.5 to r = 5? Can you describe the amount of energy needed as they move apart from each other?