# Steel bars each of length 3m at 28C are to be used for constructing a rail...

Question 483
A
1.2x $$10^{-1}cm$$
B
7.2x$$10^{-1}cm$$
C
6x$$10^{-1}cm$$
D
3.6x$$10^{-1}cm$$
E
1.8x$$10^{-1}cm$$
##### Explanation
$$\alpha= \frac{\Delta{L}}{L_1\Delta\theta}; \Delta{L}=\alpha{L_1}\Delta\theta\Rightarrow 1.0\times 10^{-5}\times 3\times (40-28)= 3.6\times 10^{-2}$$

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