Physics

Problem

40^\circ\text{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 from

40^\circ\text{C}

20^\circ\text{C}

it regains its original length of 0.2 m. The value of M is close to : (Coefficient of linear expansion and Young's modulus of brass are

10^{-5}/^\circ\text{C}

and

10^{11} \text{ N/m}^2

, respectively;

g = 10 \text{ ms}^{-2}

) a. 9 kg b. 0.5 kg c. 1.5 kg d. 0.9 kg