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A rod of length 2 m rests on a smooth horizontal floor. The rod is heated uniformly from 0 deg C to 20 deg C. Given the coefficient of linear expansion alpha = 5 * 10⁻⁵ /deg C, what is the longitudinal strain developed in the rod?
- 10⁻³
- 2 * 10⁻³
- Zero
- None
Correct answer: Zero
Solution
Because the rod rests on a frictionless surface with no constraints at its ends, it expands freely. There is no internal stress, and therefore no longitudinal strain — only a change in length (thermal expansion, not strain in the mechanical sense).
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