An aluminum bar 2.0 m long is heated from 20°C to 120°C. If aluminum's coefficient of linear thermal expansion is α = 2.4 × 10⁻⁵ /°C, by how much does its length change?
A0.24 mm
B4.8 mm
C48 mm
D48 m
Explanation
📌 ΔL = α × L × ΔT = (2.4 × 10⁻⁵) × 2.0 × (120 − 20) = (2.4 × 10⁻⁵) × 2.0 × 100 = 4.8 × 10⁻³ m = 4.8 mm. Distractor A missed a factor of 20; C is off by factor of 10 (unit conversion slip); D wildly off (used m instead of mm).