- #1

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## Homework Statement

## Homework Equations

## The Attempt at a Solution

I tried to use the equation introduced in the class, E=σε/2

ε=αΔT =2*10

^{-5}*200 = 4*10

^{-3}

and by σ=Yε, I get σ=110*10

^{9}*4*10

^{-3}= 4.4*10

^{9}

so E=(4*10

^{-3}) * (4.4*10

^{9}) /2 = 880000J

Why am I wrong?

The correct answer is 35.2 J