The work done on a particle of mass m by a force $\overrightarrow{\mathrm{F}}=\frac{\mathrm{k}(\mathrm{x}\hat{\mathrm{i}}+\mathrm{y}\hat{\mathrm{j}})}{{\left(\sqrt{{\mathrm{x}}^2+{\mathrm{y}}^2}\right)}^3}$ (where k being a constant), when the particle is taken from the point (a,0) to the point (0,a) along a circular path of radius a about the origin in the XY plane, is