1) The relative change in length (contraction) is
ϵ=L0L0−L=L0L0−L0(1+αΔT), ϵ=L0L0−L0(1+α(−20−70))=1.53⋅10−3. The stress is
σ=Eϵ=(210⋅109)(1.53⋅10−3)=321.3⋅106 Pa. This is axial stress.
2) The equation for the heat supplied is
Q=cm(Tf−Ti), Tf=cmQ+Ti=460⋅0.018751000+20=136°C.
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