Mg=(lAY)Δl
lΔl=αΔT
Mg=(AY)αΔT
M=g(AY)αΔT=10π×(0.001)2×1011×10−5×20=2π
Closest value of M is 9 kg.
JEE Main 2019 — Physics Thermodynamics
At 40∘C, a brass wire of 1mm 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∘C to 20∘C it regains its original length of 0.2m. The value of M is close to:
(Coefficient of linear expansion and Young’s modulus of brass are 10−5/∘C and 1011N/m2, respectively; g=10ms−2 )
Held on 12 Apr 2019 · Verified 6 Jul 2026.
0.9kg
0.5kg
1.5kg
9kg
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