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A 2 m rod lies on a smooth (frictionless) horizontal floor and is heated from 0 C to 20 C. The coefficient of linear expansion is alpha = 5 x 10⁻⁵ per C. What longitudinal strain develops in the rod?

1. 10⁻³
2. 2 x 10⁻³
3. Zero
4. None

Correct answer: Zero

Solution

Since the rod can freely expand on a frictionless floor, no opposing force acts, so the elastic (mechanical) longitudinal strain is zero.

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