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An iron bar (Young's modulus = 10¹¹ N/m², coefficient of linear expansion alpha = 10⁻⁶ /deg C), 1 m long and 10⁻³ m² in cross-section, is heated from 0 deg C to 100 deg C while clamped so it cannot expand or bend. Find the compressive force developed in the bar.

1. 10⁴ N
2. 10⁵ N
3. 10⁶ N
4. 10⁷ N

Correct answer: 10⁴ N

Solution

F = Y*alpha*dT*A = 10¹¹ * 10⁻⁶ * 100 * 10⁻³ = 10⁴ N.

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