A beam has the same section throughout its length with moment of inertia \(I = 1 \times 10^8 \, \text{mm}^4\). It is subjected to a uniform BM = 40 kN·m, \(E = 2 \times 10^5 \, \text{N/mm}^2\). What is the radius of curvature of the circle into which the beam will bend in the form of an arc of a circle?