A circular steel plate of radius 15 cm is cooled from 300∘C to 80∘C.

Question

Part A
By what percentage does the plate's area decrease?

Answer 1

for stell α=(11-13) •10⁻⁶ K⁻¹
take α=12•10⁻⁶ K⁻¹

ΔA=A₀2 αΔT
ΔA•100%/A₀=2αΔT•100%=
=2•12•10⁻⁶ 220•100%= 0.528%