Answer:
0.04 °C⁻¹
Explanation:
First, we need to calculate linear expansivity, then after finding that value, we can move on to finding the area expansivity.
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Finding Linear Expansivity :
⇒ α = Final length - Original length / (Original length × ΔT)
⇒ α = 9 - 4 / (4 × 70 - 20)
⇒ α = 5 / 5 × 50
⇒ α = 0.02
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Finding Area Expansivity :
⇒ Area Expansivity = 2 × Linear Expansivity
⇒ β = 2 × α
⇒ β = 2 × 0.02
⇒ β = 0.04 °C⁻¹
