The figure shows two boxes with identical square crosssections and heights \(h_1\) and \(h_2\ (h_1 = 2h_2)\) are made of different materials. An equal force is applied on the square cross-sections such that the deformations \(\theta _1\) and \(\theta_2\) are realized \((\theta _1 = 2\theta _2).\) If shear modulus of box 1 is \(4\times 10^9 \ N/m^2\) and that of box 2 is \(x \times 10^9\ N/m^2,\) then x is ________.
