Answer:
635 degree.
Explanation:
L = L₁ + L₁ X α X ΔT
L is length after expansion , L₁ is length before expansion ,α is coefficient o linear expansion and ΔT is rise in temperature.
For steel , α is 13 x 10⁻⁶ and for aluminium it is 24 x 10⁻⁶. Let common temperature required be T.
Using the formula for steel
L( steel ) = 3 + 3 x 13 x 10⁻⁶ ( T -20)
Using the formula for aluminium
L( Aluminium ) = 2.98 + 2.98 x 24 x 10⁻⁶ x ( T-20)
L( Steel ) = L( Aluminium )
3 + 3 x 13 x 10⁻⁶ ( T -20) =2.98 + 2.98 x 24 x 10⁻⁶ x ( T-20)
T = 635 degree .
