Question

The radius of a circular sheet of copper measured at 25°C was 20 cm. The change in area of the sheet when temperature is increased ti thrice the initial temperature is.(Coefficient of linear expansion of copper is 17 x 106/°C​

Answer 1

$\huge \fbox \purple{❥ Answer}$

Initial area A=π(35)2=3846.5cm2

Change in area on heating ΔA=14.5cm2

α=1.7×10−5

We know that area expansion coefficient is twice of linear expansion coefficient.

So β=2α=2×1.7×10−5=3.4×10−5

So ΔA=AβΔt

14.5=3846.5×3.4×10−5×ΔT 

ΔT=110.8oC

Answer 2

Initial area A=π(35)2=3846.5cm2

Change in area on heating ΔA=14.5cm2

α=1.7×10−5

We know that area expansion coefficient is twice of linear expansion coefficient.

So β=2α=2×1.7×10−5=3.4×10−5

So ΔA=AβΔt

14.5=3846.5×3.4×10−5×ΔT

ΔT=110.8oC