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Steel has an elastic limit of 8 x 10⁸ N/m² and Young's modulus 2 x 10¹¹ N/m². Find the maximum elongation possible for a 0.5 m long steel wire without exceeding its elastic limit.

1. 2 mm
2. 4 mm
3. 1 mm
4. 16 mm

Correct answer: 2 mm

Solution

Strain = 8e8 / 2e11 = 4e-3; elongation = 4e-3 * 0.5 = 2e-3 m = 2 mm.

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