Force and Motion: Newton's Laws - Physics (Undergraduate Foundation)

This course transitions from kinematics to dynamics, covering the cause of motion: force. It provides a complete, rigorous treatment of Newton's three laws of motion, which are the foundational principles of all classical mechanics. Mastery of these laws is non-negotiable for any study of physics or engineering. Newton's laws are not just historical principles; they are the operational framework for analysing every mechanical system, from planetary orbits to vehicle collisions and structural engineering. Understanding these laws provides the essential toolset for solving any problem involving the interaction of forces and objects. By the end of this course, you will be able to state and explain Newton's three laws of motion, analyse the forces acting on an object using free-body diagrams, and apply the second law (F=ma) to solve for acceleration, mass, or net force in standard mechanics problems. This course is a mandatory component for all first-year university students of physics and engineering. It directly follows the study of kinematics and is the absolute prerequisite for more advanced topics like work, energy, and momentum.

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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.
[NUC Core] PHY 101: General Physics I - Mechanics
[NUC Core] PHY 101: General Physics I - Mechanics
This learning track provides a complete and rigorous treatment of introductory classical mechanics as specified by the NUC Core Curriculum. It is structured to build a comprehensive analytical framework, starting with the mathematical description of motion (kinematics) and progressing through its causes (Newtonian dynamics), the powerful conservation laws, the dynamics of rotating systems, and finally, the principles of universal gravitation. Mastery of this material is the non-negotiable foundation for all subsequent study in physics and engineering. The principles of classical mechanics are the operational language for analysing the physical world. This track provides the essential toolset for solving problems in every field of engineering, from aerospace to civil, and for understanding phenomena from the trajectory of a projectile to the orbits of planets. By the end of this track, you will be able to analyse motion using vectors and calculus, apply Newton's laws to solve any standard dynamics problem, use conservation laws to analyse complex systems and collisions, analyse rotational motion, and solve problems in celestial mechanics. This learning track is a mandatory prerequisite for all first-year university students of physics, engineering, and related physical sciences. It provides the foundational knowledge required for all subsequent courses in mechanics, electromagnetism, thermodynamics, and modern physics.

This learning track provides a complete and rigorous treatment of introductory classical mechanics as specified by the NUC Core Curriculum. It is structured to build a comprehensive analytical framework, starting with the mathematical description of motion (kinematics) and progressing through its causes (Newtonian dynamics), the powerful conservation laws, the dynamics of rotating systems, and finally, the principles of universal gravitation. Mastery of this material is the non-negotiable foundation for all subsequent study in physics and engineering. The principles of classical mechanics are the operational language for analysing the physical world. This track provides the essential toolset for solving problems in every field of engineering, from aerospace to civil, and for understanding phenomena from the trajectory of a projectile to the orbits of planets. By the end of this track, you will be able to analyse motion using vectors and calculus, apply Newton's laws to solve any standard dynamics problem, use conservation laws to analyse complex systems and collisions, analyse rotational motion, and solve problems in celestial mechanics. This learning track is a mandatory prerequisite for all first-year university students of physics, engineering, and related physical sciences. It provides the foundational knowledge required for all subsequent courses in mechanics, electromagnetism, thermodynamics, and modern physics.

Course Chapters

1. Introduction
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This chapter introduces the foundational concepts of dynamics. It moves beyond describing motion to explaining its causes by defining force, mass, and inertia, which are the core components of Newton's laws. Key objectives include understanding the course structure and the fundamental definitions of force as an interaction, and mass as a measure of inertia.

Chapter lessons

1-1. Welcome

A direct statement of the course's purpose and structure. This lesson outlines the progression through Newton's three laws and their application to problem-solving in mechanics.

1-2. The concept of force

Formally defines force as a push or a pull that can cause an object to accelerate. It introduces the vector nature of force and the concept of a net or resultant force.

1-3. Mass and inertia

Defines mass as the quantitative measure of inertia, which is an object's resistance to a change in its state of motion. The distinction between mass and weight is established.

2. Newton's First Law
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This chapter focuses on Newton's First Law of Motion, the principle of inertia. It establishes the conditions for equilibrium and defines the concept of an inertial frame of reference, the context in which all of Newton's laws are valid. Key topics include the law of inertia, the definition of inertial frames, and the application of the first law to objects in static and dynamic equilibrium.

Chapter lessons

2-1. The law of inertia

States Newton's First Law: an object remains at rest or in uniform motion in a straight line unless acted upon by a net external force. This is the principle of inertia.

2-2. Inertial frames of reference

Defines an inertial frame of reference as a non-accelerating frame in which Newton's First Law holds true. This concept is critical for the correct application of all three laws.

2-3. The meaning of equilibrium

Explains that an object is in equilibrium when the net force acting on it is zero. This applies to objects at rest (static equilibrium) and those moving at a constant velocity (dynamic equilibrium).

3. Newton's Second Law
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This chapter provides a complete treatment of Newton's Second Law of Motion. It establishes the fundamental relationship between net force, mass, and acceleration (F=ma), which is the central equation of dynamics. Key topics include the second law, the use of free-body diagrams to analyse forces, and the application of the law to problems involving friction and inclined planes.

Chapter lessons

3-1. Force, mass, and acceleration

Formally states Newton's Second Law. It establishes that the acceleration of an object is directly proportional to the net force and inversely proportional to its mass.

3-2. Free-body diagrams

Introduces the free-body diagram as the essential tool for applying Newton's laws. It details the process of isolating an object and representing all external forces acting upon it.

3-3. Common forces in mechanics

Provides an overview of common forces encountered in mechanics problems. This includes gravity (weight), normal force, tension, and friction.

4. Newton's Third Law
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This chapter covers Newton's Third Law of Motion, the principle of action and reaction. It explains that forces always occur in equal and opposite pairs, a concept critical for understanding the interaction between objects. Key topics include the definition of action-reaction pairs and the application of the third law to analyse contact forces and interacting systems.

Chapter lessons

4-1. Action-reaction pairs

States Newton's Third Law: for every action, there is an equal and opposite reaction. This lesson clarifies that these forces act on different objects and are of the same type.

4-2. Applying the third law

Explains how the third law is applied in various physical situations, such as propulsion and contact forces. It addresses common misconceptions about the law.

5. Impulse and Momentum
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This chapter introduces the concepts of linear momentum and impulse. It culminates in one of the most important principles in physics: the law of conservation of linear momentum, which is essential for analysing collisions and explosions. Key topics include the definitions of momentum and impulse, the impulse-momentum theorem, and the application of momentum conservation to solve collision problems.

Chapter lessons

5-1. Defining impulse and momentum

Formally defines linear momentum as the product of mass and velocity (p=mv) and impulse as the product of force and time (J=FΔt).

5-2. The impulse-momentum theorem

Establishes the impulse-momentum theorem, which states that the impulse applied to an object is equal to the change in its momentum. This is a direct consequence of Newton's Second Law.

5-3. Conservation of linear momentum

Introduces the law of conservation of linear momentum. It states that the total momentum of an isolated system remains constant.

6. Conclusion
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This chapter consolidates the principles of Newtonian dynamics. It provides a structured summary of Newton's three laws of motion and the concept of momentum conservation, reinforcing the core of classical mechanics. The conclusion summarises the three laws and the momentum principle. It also provides a forward look to the next course, where the concepts of work and energy will provide an alternative approach to solving mechanics problems.

Chapter lessons

6-1. Summary of Newton's laws

A concise review of Newton's three laws and the principle of conservation of momentum. This lesson ensures all the foundational principles of dynamics are consolidated.

6-2. Preparing for work and energy

Explains how Newton's laws provide the foundation for the concepts of work and energy, which offer a powerful alternative method for analysing mechanical systems.