A metal rod has a length of 100cm at 200\(^oC\). At what temperature will its length be 99.4cm. If the linear expansivity of the material of the rod is 2 x 10\(^{-5}C^{-1}\)
A. 200\(^o\)C B. 300\(^o\)C C. 100\(^o\)C D. -100\(^o\)C
Correct Answer: D
Explanation
L\(_1\) = 100cm, T\(_1\) = 200\(^o\)C L\(_2\) = 99.4cm,T\(_2\) = ? \(\alpha\) = 2 x 10\(^{-5}\)C\(^{-1}\) \(\alpha\) = \(\frac{L_2 - L_1}{L_1(T_2 - T_1)}\) 2 x 10\(^{-5} = \frac{100- 99.4}{100(200 - T_2)} = \frac{0.6}{100(200 - T_2)}\) 2 x 10\(^{-5}\) x \(100(200 - T_2) = 0.6\) \(200 - T_2 = \frac{0.6}{0.002} = 300^oC\) \(T_2 = 200 - 300 = -100^oC\) Â Â Â
