The Young's modulus of a steel wire of length 6 m and cross-sectional area $3 \mathrm{~mm}^2$, is $2 \times 11^{11} \mathrm{~N} / \mathrm{m}^2$. The wire is suspended from its support on a given planet. A block of mass 4 kg is attached to the free end of the wire. The acceleration due to gravity on the planet is $\frac{1}{4}$ of its value on the earth. The elongation of wire is (Take g on the earth $=10 \mathrm{~m} / \mathrm{s}^2$ ):