A brass rod length 50 cm and diamteer 3.0 mm is joined to a steel rod of the same length and diameter. What is the change in length of the combined rod at `250^(@)C` if the original length are at `40^(@)C` ? Coefficient of linear expansion of brass and steel are `2.10xx10^(-5) .^@C^(-1)` and `1.2 xx 10^(-5) ^(@)C^(-1)` respectively.

Explanation

`Delta L_1 = L_1 alpha_1 Delta T =50 xx(2.10xx10^(-5)) (250 - 40) = 0.2205 cm`
`Delta L_2 = L_2 alpha_2 Delta T =50 (1.2xx10^(-5)) (250 - 40) =0.126 cm`
:. Change in length of combined rod ` =Delta L_1 + Delta L_2 = 0.220 + 0.126 = 0.346 cm`