Center of Gravity

Grade 11 · Physics

Semester 1 | Period 2 | Week 10

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Subject: Physics

Semester: 1

Period: 2

Week: 10

School Name:

Teacher’s Name:

Subject: Physics

Grade Level: Grade 11

Week & Period: Week 10, Period II

Date:

Sub-topic: Center of Gravity

Learning Objectives

By the end of this lesson, learners will:

  1. Define center of gravity and center of mass.
  2. Distinguish between center of gravity and center of mass.
  3. Identify the position of center of gravity for simple shapes.
  4. Explain the effect of center of gravity on stability.

 

Previous Knowledge

Basic equilibrium and moments.

 

Instructional Materials

  • Cut-out shapes of cardboard (square, rectangle, triangle)
  • Pin or nail for suspension
  • Weights
  • Meter rule

 

Anticipation (Warm-Up) – 5 minutes

Ask:

  • “What happens if you balance a ruler on your finger?”
  • “Why do tall buildings not topple easily?”

 

Building Knowledge (Main Lesson) – 25 minutes

  1. Center of Gravity (CG):
  • The point through which the entire weight of an object acts.
  • Can be inside or outside the object.
  1. Center of Mass:
  • The average position of all the mass in the body.
  • For uniform gravitational field, CG coincides with center of mass.
  1. Finding CG:
  • Suspend an object from a point, draw vertical line downwards.
  • Repeat from different suspension points; intersection is CG.
  1. Stability:
  • A body is stable if CG lies below the base of support.
  • Tall objects have higher CG and less stability.

 

Experiment:

Finding the center of gravity of a cardboard shape

Materials: Cardboard shapes, pins, pencil, ruler

Procedure:

  • Suspend the shape from one point, mark vertical line.
  • Repeat suspension from another point and mark line.
  • Intersection of lines is CG.

 

Learners’ Activities

  • Find CG of various shapes using suspension method.
  • Discuss effects of CG on everyday objects.

 

Consolidation (Review and Assessment) – 10 minutes

Oral Questions:

  • Define center of gravity.
  • How do you find CG experimentally?
  • Why does a low CG make an object more stable?

 

Homework / Assignment

  • Find and mark CG of a triangular cardboard piece.
  • List three objects with low CG and explain why.

 

Notes – Detailed and Explained

  • CG affects balance and stability.
  • Engineers design structures with low CG for safety.
  • Suspension method is a reliable way to locate CG.

 

Expanded Notes / Instructions

  • Include diagrams of suspension method.
  • Discuss real-life implications (cars, buildings).

Inclusive / Differentiation

  • Hands-on for kinesthetic learners.
  • Diagrams for visual learners.

 

Teacher’s Reflection

  • Were students able to perform suspension method?
  • Did they grasp the significance of CG?