Topic Cluster

Classical Mechanics

Classical mechanics: forces, energy, momentum and motion — Newton’s laws, work and energy, collisions, rotation and the everyday mechanics the rest of physics is built on.

What Is Classical Mechanics?

Classical Mechanics is the physics of why motion changes: the forces, energy and momentum that govern everything from a rolling ball to an orbiting satellite. Everything else in physics leans on it.

Core equations in classical mechanics
Relationship	Equation	What it tells you
Newton's second law	F = m·a	Net force, mass and acceleration
Work done	W = F·d·cosθ	Energy transferred by a force
Kinetic energy	KE = ½·m·v²	Energy of a moving mass
Gravitational PE	PE = m·g·h	Energy stored by height
Momentum	p = m·v	Conserved in every collision
Torque	τ = r·F·sinθ	Turning effect of a force

Share this topic

Classical Mechanics

Escape Velocity Explained: Formula, Five Worlds and Worked Examples

Escape velocity is the launch speed at which an unpowered object leaves a world for good: 11.18 km/s at Earth's surface, 2.375 km/s at the Moon's and 617.8 km/s at the Sun's. This page derives v = sqrt(2GM/r) from energy conservation, puts five worlds side by side against NASA's own published figures, shows why half the escape speed lifts a projectile only one third of a radius, and explains why no rocket ever has to reach 11.2 km/s. Seven worked problems, two original diagrams, an interactive lab and a calculator.

19 min read

Classical Mechanics

Tangential Acceleration: What a = v2/r Leaves Out When the Speed Changes

Tangential acceleration is the rate at which speed changes along the path, and it is the term a = v2/r has nowhere to put. Add it and the acceleration an object actually has stops pointing at the centre of the bend: two perpendicular components, combined as the sides of a right-angled triangle.

20 min read

Classical Mechanics

Angular Momentum Explained

Angular momentum is an object's moment of inertia multiplied by its spin rate, L = Iω, and for one mass on a circle the same quantity is L = mvr. Why a spinning skater speeds up when nothing pushes on them, where the extra 29.33 J of energy actually comes from, why the answer changes when you change the axis, seven worked problems, three diagrams and an interactive lab.

23 min read

Classical Mechanics

Conservation of Energy Explained

Conservation of energy says the total never changes: kinetic energy plus potential energy stays constant unless something carries energy away as heat, sound or deformation. Why a heavy ball and a light one arrive at the same speed, why the shape of the slope makes no difference, where the energy of a fading bounce actually goes, eight worked problems, three diagrams and an interactive simulator.

19 min read

Classical Mechanics

The Work-Energy Theorem, Step by Step

The work energy theorem says the net work done on a body equals the change in its kinetic energy - add up what every force did, signs included, and the total tells you the speed. A four-step method, when to use it instead of SUVAT, why a car braking from 60 m/s needs exactly four times the road it needs from 30, eight worked problems, three diagrams and an interactive simulator.

22 min read

Classical Mechanics

Kepler’s Laws of Planetary Motion

Kepler's laws describe every planetary orbit: an ellipse with the Sun at one focus, equal areas swept in equal times, and T² = a³ in years and AU. The three laws with scale diagrams, JPL data for all eight planets, Newton's explanation, seven worked problems and an orbit lab.

21 min read

Classical Mechanics

Newton’s Law of Gravitation

The law of gravitation says every mass attracts every other mass, with the pull falling off as the square of the distance. Here is the formula, what each symbol means, seven worked problems and the inverse-square mistake almost everyone makes.

14 min read

Classical Mechanics

Free Body Diagram: How to Draw One Step by Step

A free body diagram shows one object on its own with an arrow for every external force acting on it. This guide covers the five steps to draw one, the four forces that never belong, and eight worked problems solved in full.

16 min read

Classical Mechanics

Centrifugal Force vs Centripetal Force

Centrifugal force is the outward push you feel in a turn, but it only exists in a rotating frame. Here is how it differs from centripetal force, with examples, worked problems and an interactive lab.

15 min read

Classical Mechanics

Physics Unit Conversions: N, J, Pa, K and More

A practical reference for physics unit conversions, covering force, energy, pressure, temperature and SI prefixes with exact factors and worked examples.

13 min read

Classical Mechanics

Common Physics Misconceptions Students Get Wrong

Twelve physics misconceptions that survive years of teaching, from heavier objects falling faster to current being used up, each corrected with the actual physics, worked examples and an interactive free-fall lab.

18 min read

Classical Mechanics

Physics Symbols: Greek Letters and Notation Cheat Sheet

A complete cheat sheet of physics symbols: all 24 Greek letters, the everyday Latin symbols, notation rules and constant symbols, each with its SI unit. Includes worked decoding problems and the symbol mix-ups that cost marks.

10 min read

1 2 3 … 5 Next →