At 40o 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 40oC to 20oC 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
/oC and 1011 N/m
2
, respectively; g=
10 ms–2
)