Chapter 4 — Laws of Motion

Laws of Motion comprises Newton's three fundamental laws that govern how forces affect the motion of bodies: the law of inertia, the relationship between force and acceleration, and the principle that forces always occur in equal and opposite pairs.

Chapter 4 explores Newton's laws of motion, starting with Galileo's law of inertia and progressing through the first law (if net force is zero, acceleration is zero), second law (F = dp/dt = ma), and third law (forces occur in equal and opposite pairs). The chapter covers momentum, impulse, equilibrium, common forces including friction (static and kinetic), and applications to circular motion, providing the foundation for understanding mechanics.

1. 01Newton's First Law: A body at rest or in uniform motion remains so unless acted upon by net external force; this is inertia, not the absence of forces
2. 02Newton's Second Law: F = dp/dt = ma expresses that force is proportional to rate of change of momentum and acts in the direction of acceleration
3. 03Newton's Third Law: Forces always occur in pairs between two bodies; action and reaction are simultaneous and equal-opposite but act on different bodies
4. 04Momentum p = mv is the product of mass and velocity; impulse equals force × time interval and equals change in momentum
5. 05Static friction opposes impending motion (fs ≤ μsN); kinetic friction opposes actual relative motion (fk = μkN), with μk < μs
6. 06Conservation of momentum: total momentum of an isolated system remains unchanged regardless of internal forces; collision example shows pb + pg = 0