delta S = ?
So = 40
To = 0
Beta = 48.10^-6
delta S = So.B.(T- To)
delta S = 40.48.10^-6(60-0)
delta S = 40.10^-6.60
delta S = 2400.10^-6
delta S = 0,0024 cm²
Sf = So + delta S
Sf = 40 + 0,0024cm
Sf = 40,0024cm²
B)
delta S = ?
To = 0
Tf = -30
So = 40
B = 48.10^-6
delta S = So.B(T-To)
delta S = 40.10^-6(-30-0)
delta S = 40.10^-6.(-30)
delta S = -1200.10^-6
delta S = -0,0012cm²
Sf = So + delta S
Sf = 40 + (-0,0012)
Sf = 40 - 0,0012
Sf = 39,9988cm²