Thermal Expansion — A/L Physics

How do I practise Thermal Expansion?

1 question with a worked solution

1. A glass flask of volume 500 cm³ is completely filled with mercury at 20 °C. The linear expansivity of the glass is α = 8.0 × 10⁻⁶ K⁻¹ and the real volume expansivity of mercury is γ_r = 1.80 × 10⁻⁴ K⁻¹. If heated to 100 °C, what volume of mercury overflows from the flask?
   1. A) 8.12 cm³
   2. B) 7.20 cm³
   3. C) 6.24 cm³
   4. D) 5.40 cm³
   Check my answer

   Correct answer: C) 6.24 cm³

   Volume expansivity of glass container is γ_g = 3α = 3 × 8.0 × 10⁻⁶ = 2.4 × 10⁻⁵ K⁻¹. Apparent volume expansivity of mercury is γ_a = γ_r - γ_g = 1.80 × 10⁻⁴ - 0.24 × 10⁻⁴ = 1.56 × 10⁻⁴ K⁻¹. Overflow volume ΔV = V₀ γ_a ΔT = 500 cm³ × (1.56 × 10⁻⁴ K⁻¹) × (100 - 20) K = 500 × 1.56 × 10⁻⁴ × 80 = 6.24 cm³.

   Show worked solution

   Step 1: γ_g = 3α = 3 × 8.0 × 10⁻⁶ = 2.4 × 10⁻⁵ K⁻¹. Step 2: γ_a = γ_r - γ_g = 1.80 × 10⁻⁴ - 0.24 × 10⁻⁴ = 1.56 × 10⁻⁴ K⁻¹. Step 3: ΔV = V₀ · γ_a · ΔT = 500 × 1.56 × 10⁻⁴ × 80 = 6.24 cm³. Answer: 6.24 cm³.
   Modelled on: the A/L Physics examination pattern

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Where does Thermal Expansion fit in the syllabus?

Unit 4.2 · Year 1 · Term 2