JEE Main 2022 · 26 Jul · Shift 2, Physics question 55

A uniform heavy rod of mass 20 kg, cross sectional area 0.4 m$^2$ and length 20 m is hanging from a fixed support. Neglecting the lateral contraction, the elongation in the rod due to its own weight is $x\times10^{-9}$ m. The value of $x$ is ______.

(Given, young modulus Y = $2\times10^{11}$ Nm$^{-2}$ and g = 10 ms$^{-2}$)