TS EAMCET Medical 10 AUG 2021 Shift 1 Paper

Two pieces of ralls each of length 20m are laid down (end - to -end) when the temperature of surrowding is 25∘C. What must be the space left between them so as to allow expansion when the surrounding temperature goes up to 4‌5C.
[Coefficient of linear expression for rail is 0.000015C−1]