Basic Physics · SHS3 Physics

Lesson notes

Learning Objectives

Indicator: 3.1.1.LI.4 - Calculate the reactions provided by supports.

By the end of the lesson, learners can:

Define reaction force and explain why supports exert upward forces on loaded beams.
Apply the principle of moments to set up equations for reactions at two supports.
Use the conditions for equilibrium (sum of upward forces equals sum of downward forces, and sum of clockwise moments equals sum of anticlockwise moments) to calculate reactions at supports.
Solve problems involving a beam supported at two points carrying one or more loads, presenting answers in newtons (N).
Verify answers to reaction problems by checking that the calculated reactions satisfy both equilibrium conditions.

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Curriculum details

Strand: Mechanics and Matter (Strand 1)
Sub-strand: Basic Physics (1.1)
Content standard: 3.1.1.CS.1 - Demonstrate knowledge and understanding of moments 3.1.1.LO.1 Use the concept of moments to determine the mass of a body
Indicator: 3.1.1.LI.4 - Calculate the reactions provided by supports.
Suggested placement: Semester 1, Week 2 (Week 2 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. 149

Exemplars (from the NaCCA curriculum)

Enquiry learning From the experiment, let learners brainstorm and come out with the reaction provided by knife edge.
Provide equitable access to resources and opportunities.
Assessment (3.1.1.AS.4). The document marks these depth-of-knowledge levels for this indicator: Level 3 Strategic reasoning.
Teaching and Learning Resources:
- Metre rule,
- Standard masses,
- Knife edge
- Unknown masses. E.g., Stone, erasers, reference internet. books,