| Lesson Plan |
| Grade: Year 12 (A‑Level) |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that, when there is no resultant force and no resultant torque, a system is in equilibrium |
Learning Objective/s:
- Describe the two conditions for translational and rotational equilibrium (ΣF = 0 and Στ = 0).
- Apply equilibrium equations to determine unknown forces in static systems.
- Construct accurate free‑body diagrams and select convenient axes for torque calculations.
- Identify and correct common errors such as sign conventions and omitted forces.
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Materials Needed:
- Projector and screen
- Whiteboard and markers
- Printed worksheet with beam diagram and practice questions
- Force/torque demonstration kit (spring scales, meter sticks, pivot)
- Calculators
- Student notebooks
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Introduction:
Begin with a quick demonstration of a balanced ruler on a finger to capture interest. Review Newton’s first law and the idea of net force on a stationary object. Explain that today’s success criteria are to identify when both net force and net torque are zero and to use this knowledge to solve static problems.
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Lesson Structure:
- Do‑now (5’) – Short question on net force for a stationary object; teacher checks responses.
- Mini‑lecture (10’) – Define resultant force and torque, present ΣF = 0 and Στ = 0, demonstrate with the balanced ruler.
- Guided practice (15’) – Whole‑class draw a free‑body diagram of the supported beam and write the two equilibrium equations.
- Collaborative problem solving (15’) – Small groups solve the ladder problem, choosing an axis and applying sign conventions.
- Whole‑class debrief (10’) – Groups share solutions; teacher highlights common mistakes and unit checks.
- Exit ticket (5’) – Students write one correct equilibrium equation and one common error to avoid.
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Conclusion:
Recap that static equilibrium requires both ΣF = 0 and Στ = 0 and that careful diagramming prevents sign errors. Collect the exit tickets to gauge understanding. Homework: complete the remaining practice questions on the worksheet, focusing on free‑body diagrams and torque calculations.
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