Question

Find the final temperature of a copper rod whose area of cross section changes from 10 m² to 11 m²due to heating. The copper rod is initially kept at 90 K. (Coefficient of superficial expansion is 0.0021 /K).

Answer 1

Change in area ΔA = 11 – 10 = 1 m² 

Initial temperature T₁ = 90 K 

Let Final temperature be T₂ K 

A₀ = 10 m²

Coefficient of superficial expansion is 

α_A = 0.0021 / k

\(\frac{ΔA}{A_0}\) = α_A ΔT

\(\frac{1}{10}\) = 0.0021 ΔT

∴ ΔT = 0.0021 x 10

= 0.021

T₂ - T₁ = 0.021

T₂ – 90 = 0.021 

∴ Final temperature T₂ = 90.021 K