A metal rod has a length of 100cm at 200 oC At ... - JAMB Physics 2019 Question
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 option: d
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 \(100(200 - T_2) = 0.6\)
\(200 - T_2 = \frac{0.6}{0.002} = 300^oC\)
\(T_2 = 200 - 300 = -100^oC\)
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