Two blocks of mass \( 2 \, \text{kg} \) and \( 4 \, \text{kg} \) are connected by a metal wire going over a smooth pulley as shown in figure. The radius of wire is \( 4.0 \times 10^{-5} \, \text{m} \) and Young’s modulus of the metal is \( 2.0 \times 10^{11} \, \text{N} / \text{m}^{2} \). The longitudinal strain developed in the wire is \( \dfrac{1}{\alpha \pi} \). The value of \( \alpha \) is __________. [Use \( g = 10 \, \text{m} / \text{s}^{2} \)]
