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Not Everything That Stops Working Has Lost Its Value Feeling broken by life's setbacks? Discover why your value never decreases because of failure, pain, or difficult seasons. Learn the powerful lesson behind the broken machine and why your worth remains unchanged. The Broken Machine That Changed Everything Imagine walking into a workshop and finding an old industrial machine covered in dust and rust. It has not worked for years. Most people pass it without a second thought. "It is finished." "It is useless." "It belongs in the scrapyard." Those are the words many would use. Then an experienced engineer enters. Instead of seeing a useless machine, he sees possibility. He opens the casing, examines the internal parts, replaces a few worn components, reconnects the wiring, and powers it on. Within moments, the machine is running again. What changed? Not its value. Only its condition. That simple scene teaches one of the most important lessons about human...

EQUILIBRIUM OF FORCES

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Equilibrium of Forces — Edwin Ogie Library

Comprehensive e-book: static & dynamic equilibrium, resultant & equilibrant forces, torque, moments, worked examples and a CBT quiz for JSS/Senior students.

Keywords: equilibrium, torque, moments Edwin Ogie Library

Introduction

An object is in equilibrium if it experiences no acceleration — i.e. the net force and net moment acting on it are zero. This e-book covers translational and rotational equilibrium and practical worked examples for classroom and exam preparation.

Equilibrium diagram

Quick links: Edwin Ogie Library (home)CBT Quiz

Forms of Equilibrium

Translational (Linear) Equilibrium

No net force — body at rest or moving with constant velocity (ΣFx = 0, ΣFy = 0).

Rotational Equilibrium

No net torque — sum of clockwise moments = sum of anticlockwise moments (ΣM = 0).

Resultant and Equilibrant Forces

The resultant is the vector sum of all forces. The equilibrant is equal in magnitude but opposite in direction to the resultant.

Parallelogram law  —  R² = P² + Q² + 2PQ cosθ

Example RE1: Two Forces (30 N & 40 N, θ = 60°)

Couples & Torque

A couple is two equal and opposite forces with parallel lines of action but not collinear — producing a pure rotation. Torque (moment) = Force × perpendicular distance (Nm)

Example CT1: Torque

Equilibrium of Three Forces (Triangle of Forces)

If three forces acting at a point keep a body in equilibrium, they can be arranged to form a closed triangle.

Example TF1

Moment of a Force & Principle of Moments

Moment = Force × perpendicular distance

For equilibrium, sum of clockwise moments = sum of anticlockwise moments about any pivot.

Example MM1

Metre Rule Worked Example

Problem (i): A metre rule balances at 48 cm. A 60 g mass is at 6 cm and causes the balance point to shift to 30 cm. Find mass of the rule.

Problem (ii): Move the 60 g mass to 13 cm, find new balance point x (W=80 g).

Additional Worked Examples

EQ1: Beam with two forces

A beam supported at center with 100 N and 150 N at 2 m and 3 m opposite sides — is it in equilibrium?

EQ2: Signboard with two cable tensions (vertical components)

Summary of Key Concepts

  • Equilibrium: No net force and no net moment.
  • Resultant & Equilibrant: Equilibrant balances the resultant.
  • Moment & Torque: Force × perpendicular distance (Nm).
  • Triangle of forces: Three forces in equilibrium form a closed triangle.

30-Question CBT Quiz (15 minutes)

Designed for JSS / early secondary students. Click Start Quiz to begin.

Time Remaining: 15:00
Resources: Edwin Ogie LibraryBibleGateway (for pastoral pieces) • For platform requests see Google/Twitter/Facebook help pages.

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