A brass rod has an initial length of 1.50 m at 20°C. Given that the linear expansivity of brass is 1.9 × 10⁻⁵ K⁻¹, calculate its expansion in length when heated to 120°C.
Answer and explanation
Correct answer: D. 2.85 mm
- Step 1: Temperature change: ΔT = 120 - 20 = 100 K. Step 2. Linear expansivity: ΔL = L0 α ΔT = 1.50 × (1.9 × 10⁻⁵) × 100 = 2.85 × 10⁻³ m = 2.85 mm. Answer: 2.85 mm. Why not the others: 3.42 mm uses ΔT = 120 K; 1.90 mm uses L0 = 1.0 m; 4.20 mm is an arithmetic error.
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