By the definition of thermal linear expansion, we have:
LAl,0LAl−LAl,0=αAl(tcomm−0∘C),LCu,0LCu−LCu,0=αCu(tcomm−0∘C).Then, taking into account that LAl,0=LCu,0=L0 we can rewrite our equations as follows:
LAl−L0=αAlL0tcomm,LCu−L0=αCuL0tcomm.Subtracting second equation from the first one, we get:
LAl−LCu=(αAl−αCu)L0tcomm,tcomm=(αAl−αCu)L0LAl−LCu,tcomm=(24⋅10−6 ∘C1−17⋅10−6 ∘C1)⋅1.25 m7.5⋅10−5 m=8.57∘C.
Comments
Noted. Thank you very much!! God bless