A parallel-plate capacitor with plate length \(L\), width \(w\), and plate separation \(d\) is connected to a battery that maintains a constant potential difference \(V_0\). A slab of dielectric material with dielectric constant \(\kappa > 1\) and thickness \(d\) is partially inserted a distance \(x\) between the plates, as shown in the diagram. How does the magnitude of the electrostatic force exerted on the slab at insertion distance \(x_1 = \dfrac{1}{4}L\) compare to the magnitude of the electrostatic force at insertion distance \(x_2 = \dfrac{3}{4}L\), and what is the physical reasoning for this comparison?