At 40^° C, a brass wire of 1 mm radius is hung from the ceiling. A small mass, M is hung from the free end of the wire. When the wire is cooled down…

At $\displaystyle 40^{\circ} \mathrm{C}$, a brass wire of $\displaystyle 1$ mm radius is hung from the ceiling. A small mass, M is hung from the free end of the wire. When the wire is cooled down from $\displaystyle 40^{\circ} \mathrm{C}$ to $\displaystyle 20^{\circ} \mathrm{C}$ it regains its original length of $\displaystyle 0.2$ m . The value of M is close to : (Coefficient of linear expansion and Young's modulus of brass are $\displaystyle 10^{-5} /{ }^{\circ} \mathrm{C}$ and $\displaystyle 10^{11} \mathrm{~N} / \mathrm{m}^2$, respectively ; $\displaystyle \mathrm{g}=10 \mathrm{~ms}^{-2}$ )