Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: State that, when there is no resultant force and no resultant moment, an object is in equilibrium
Learning Objective/s:
  • Describe the concepts of resultant force and resultant moment.
  • State the conditions for translational and rotational equilibrium (∑F = 0 and ∑M = 0).
  • Apply the equilibrium conditions to solve static problems involving forces and torques.
  • Explain how to calculate moments using force magnitude and perpendicular distance.
  • Interpret worked examples to determine support reactions in beam problems.
Materials Needed:
  • Projector or interactive whiteboard
  • Printed handout on equilibrium concepts
  • Worksheet with practice problems and beam diagram
  • Force‑vector and torque demonstration kit (spring scales, meter sticks)
  • Calculator for each student
  • Whiteboard and markers
 Introduction:
Begin with a quick demonstration: hang a weight from a lever and ask students what will happen if the lever stays still. Review previous learning on forces and vectors, reminding them that they can add forces vectorially. Explain that today they will learn how both forces and turning effects must balance for an object to be in equilibrium, and they will be able to state and apply the two equilibrium conditions.
Lesson Structure:
  1. Do‑now (5'): Students answer a short question on net force to activate prior knowledge.
  2. Mini‑lecture (10'): Define resultant force and resultant moment; present the equilibrium equations ∑F = 0 and ∑M = 0.
  3. Guided demonstration (10'): Use spring scales on a lever to show how equal and opposite torques produce zero net moment.
  4. Worked example (15'): Walk through the 4 m beam problem, students follow on worksheet while teacher models each step.
  5. Collaborative practice (15'): Pairs solve additional static‑equilibrium problems; teacher circulates to check reasoning.
  6. Quick check (5'): Exit ticket – write the two equilibrium conditions and give one real‑world example.
Conclusion:
Summarise that equilibrium requires both the sum of forces and the sum of moments to be zero. Review the beam example and invite a few students to share their solutions. Collect the exit tickets and assign a homework worksheet with three new static‑equilibrium problems to reinforce the concepts.