Heat · SHS3 Physics

Lesson notes

Learning Objectives

Indicator: 3.2.1.LI.2 - Calculate the linear, area, and volume expansivities of metals.

By the end of the lesson, learners can:

Recall the definitions of linear expansivity (α), area expansivity (β), and volume expansivity (γ) and state their SI units.
Apply the formula L2 = L1(1 + αΔθ) to calculate the final length, original length, expansivity, or temperature change of a metal.
Calculate the area or volume expansion of a metal object using β = 2α and γ = 3α relationships.
Solve multi-step problems involving expansions of metal strips, rods, and containers, justifying each step of the solution.
Evaluate the practical consequences of neglecting expansion in engineering and construction by interpreting calculated values.

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Curriculum details

Strand: Energy (Strand 2)
Sub-strand: Heat (2.1)
Content standard: 3.2.1.CS.1 - Demonstrate knowledge and understanding of heat as agent of expansion of states of matter. 3.2.1.LO.1 Explain how expansion occurs in solids, liquids and gases.
Indicator: 3.2.1.LI.2 - Calculate the linear, area, and volume expansivities of metals.
Suggested placement: Semester 1, Week 13 (Week 13 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 164

Exemplars (from the NaCCA curriculum)

Think pair share:
- Let learners discuss the importance of expansion and how a bimetallic strip can be used as an electric circuit breaker.
- Let learners determine the linear, superficial and cubic expansivity of solids.
Explore contributions of vulnerable groups in the class.
Assessment (3.2.1.AS.2). The document marks these depth-of-knowledge levels for this indicator: Level 1 Recall; Level 3 Strategic reasoning.
Teaching and Learning Resources:
- Audio-visuals
- Internet
- Projectors
- YouTube
- Interactive virtual laboratory