Equilibrium of Forces - Physics (Senior Secondary)
Why do structures stand still while others collapse under their own weight? This course dissects the principle of equilibrium of forces, teaching you how to analyse static systems where the net force and moment are zero. You will master the conditions for translational and rotational stability, moving beyond theory to grasp the essential mechanics that keep everything from simple bridges to complex cranes securely in place.
Understanding these laws is critical for any serious study of civil engineering, architecture, and mechanical design. Mastery here allows you to predict structural integrity, solve complex loading problems, and ensure safety in physical builds. By applying these calculations, you gain the technical foundation required to design systems that do not fail, turning abstract physics into tangible, reliable work.
By the end of this course, you will define and apply Lami's theorem and the triangle of forces with precision. You will solve problems involving coplanar forces, compute the resultant of multiple forces, and determine the exact conditions required to keep an object at rest. You will leave with the capability to model physical interactions and resolve vector problems accurately, meeting the requirements of national examinations and beyond.
This course is built for senior secondary physics students aiming for top marks in their WASSCE and UTME. It remains equally vital for undergraduates in engineering or the physical sciences who need to reinforce their fundamental knowledge, as well as anyone seeking to master the mechanical principles governing the physical world. If you require a solid grasp of how forces interact to produce stability, this material provides the necessary rigour.
$ 9.99
Enrolment valid for 12 months
This course is also part of the following learning track. You may join the track to gain comprehensive knowledge across related courses.
Physics
Physics controls every machine, building, and system you will design or maintain. This complete programme covers every topic required for the JAMB UTME physics paper. You will move past basic definitions and learn to solve exact problems using standard laws and formulas. We focus strictly on measurements, mechanics, thermal properties, waves, electricity, and modern physics. You will gain a working knowledge of the physical world without unnecessary theory.
This track suits senior secondary students preparing for WAEC, NECO, or JAMB examinations. It serves first-year university undergraduates in engineering or physical sciences who require a firm foundation. Technical beginners and independent learners who plan to enter engineering, medicine, telecommunications, or skilled trades will find these lessons essential for their next steps.
You will finish able to calculate forces, analyse electrical circuits, predict wave behaviour, and explain atomic interactions. You will interpret laboratory data, apply mathematical models to physical systems, and answer examination questions with speed and accuracy. This preparation secures high scores in national entrance tests and builds the technical base required for university engineering degrees or direct entry into professional technical work.
Physics
Physics controls every machine, building, and system you will design or maintain. This complete programme covers every topic required for the JAMB UTME physics paper. You will move past basic definitions and learn to solve exact problems using standard laws and formulas. We focus strictly on measurements, mechanics, thermal properties, waves, electricity, and modern physics. You will gain a working knowledge of the physical world without unnecessary theory.
This track suits senior secondary students preparing for WAEC, NECO, or JAMB examinations. It serves first-year university undergraduates in engineering or physical sciences who require a firm foundation. Technical beginners and independent learners who plan to enter engineering, medicine, telecommunications, or skilled trades will find these lessons essential for their next steps.
You will finish able to calculate forces, analyse electrical circuits, predict wave behaviour, and explain atomic interactions. You will interpret laboratory data, apply mathematical models to physical systems, and answer examination questions with speed and accuracy. This preparation secures high scores in national entrance tests and builds the technical base required for university engineering degrees or direct entry into professional technical work.
Physics controls every machine, building, and system you will design or maintain. This complete programme covers every topic required for the JAMB UTME physics paper. You will move past basic definitions and learn to solve exact problems using standard laws and formulas. We focus strictly on measurements, mechanics, thermal properties, waves, electricity, and modern physics. You will gain a working knowledge of the physical world without unnecessary theory. This track suits senior secondary students preparing for WAEC, NECO, or JAMB examinations. It serves first-year university undergraduates in engineering or physical sciences who require a firm foundation. Technical beginners and independent learners who plan to enter engineering, medicine, telecommunications, or skilled trades will find these lessons essential for their next steps. You will finish able to calculate forces, analyse electrical circuits, predict wave behaviour, and explain atomic interactions. You will interpret laboratory data, apply mathematical models to physical systems, and answer examination questions with speed and accuracy. This preparation secures high scores in national entrance tests and builds the technical base required for university engineering degrees or direct entry into professional technical work.
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Course Chapters
1. Introduction
1. Introduction
This chapter establishes the foundational concepts of force, equilibrium, and vector resolution that underpin the entire course. You will define equilibrium of a particle, distinguish between resultant and equilibrant, and apply the conditions for translational equilibrium under coplanar forces.
The key topics include the definition of equilibrium of a particle; the concept of resultant and equilibrant of forces; and the first and second conditions for equilibrium of coplanar forces acting on a particle.
2. Triangle of Forces
2. Triangle of Forces
This chapter introduces the triangle of forces as a graphical and analytical method for solving equilibrium problems involving three coplanar forces acting at a point. You will learn how to construct force triangles and apply them to find unknown magnitudes and directions.
The key topics include the statement and proof of the triangle of forces; graphical construction of force triangles; and the application of the triangle of forces to solve equilibrium problems with three concurrent forces.
3. Polygon of Forces
3. Polygon of Forces
This chapter extends the triangle of forces to systems of more than three concurrent forces using the polygon of forces. You will learn how to construct closed force polygons and apply them to determine unknown forces in complex equilibrium systems.
The key topics include the statement of the polygon of forces; graphical construction of force polygons for four or more forces; and the application of the polygon of forces to solve equilibrium problems involving multiple concurrent forces.
4. Lami's Theorem
4. Lami's Theorem
This chapter presents Lami's theorem as a powerful analytical tool for solving equilibrium problems involving exactly three coplanar forces acting at a point. You will derive the theorem from the sine rule and apply it to find unknown forces and angles directly.
The key topics include the statement and derivation of Lami's theorem from the triangle of forces and the sine rule; the conditions for applying Lami's theorem; and the application of Lami's theorem to solve numerical equilibrium problems efficiently.
5. Moment of a Force
5. Moment of a Force
This chapter introduces the moment of a force and the principle of moments, extending equilibrium analysis from particles to rigid bodies. You will learn how forces produce rotation and how to calculate moments about a point, including the special case of a couple.
The key topics include the definition and calculation of the moment of a force about a point; the principle of moments for a body in rotational equilibrium; the moment of a couple (torque); and practical applications of moments in everyday situations.
6. Equilibrium of Rigid Bodies
6. Equilibrium of Rigid Bodies
This chapter combines the two conditions for equilibrium to analyse rigid bodies under the action of parallel and non-parallel coplanar forces. You will apply both translational and rotational equilibrium conditions simultaneously to solve for unknown forces and positions.
The key topics include the two conditions for equilibrium of a rigid body; the equilibrium of rigid bodies under parallel coplanar forces; the equilibrium of rigid bodies under non-parallel coplanar forces; and the determination of unknown forces and reaction forces in static systems.
7. Centre of Gravity
7. Centre of Gravity
This chapter defines the centre of gravity of a body and explains its significance in determining the behaviour of objects under gravitational force. You will learn methods for locating the centre of gravity of regular and irregular bodies and understand its relationship with the centre of mass.
The key topics include the definition of the centre of gravity of a body; the distinction between centre of gravity and centre of mass; experimental and analytical methods for locating the centre of gravity; and the role of the centre of gravity in the equilibrium of bodies.
8. Types of Stability
8. Types of Stability
This chapter classifies the three types of equilibrium, stable, unstable, and neutral, based on how a body responds when slightly displaced from its equilibrium position. You will learn the conditions that determine each type and their practical implications for structural design.
The key topics include the definitions and characteristics of stable, unstable, and neutral equilibrium; the conditions for each type of stability in terms of the position of the centre of gravity and the base of support; and practical examples and applications of each type of stability.
9. Friction
9. Friction
This chapter introduces friction as a contact force that opposes relative motion between surfaces. You will distinguish between static and dynamic friction, determine the coefficient of limiting friction, and explore methods for reducing friction in practical systems.
The key topics include the definition and causes of friction; the distinction between static friction and dynamic (kinetic) friction; the coefficient of limiting friction and its determination; the laws of solid friction; advantages and disadvantages of friction; and methods of reducing friction.
10. Conclusion
10. Conclusion
This chapter provides a comprehensive review of all topics covered in the course, reinforcing the key principles and problem-solving techniques for equilibrium of forces. You will consolidate your understanding of particle and rigid body equilibrium, graphical and analytical methods, stability, and friction.
The key topics include a summary of the conditions for equilibrium of particles and rigid bodies; a review of the triangle of forces, polygon of forces, and Lami's theorem; a recap of moments, centre of gravity, and types of stability; and a consolidation of friction concepts and their applications.