# Physics Lab

> Free virtual physics laboratory that runs 100% in the browser (also offline, as an installable PWA). 61 interactive experiments with theory in English, Portuguese and Spanish. No server-side code: simulations and extensions run locally.

Key facts:
- App: https://apps-educacionais.web.app/app (deep link to an experiment: https://apps-educacionais.web.app/app#exp=<id>, language: ?lang=en|pt|es)
- Fields: mechanics, waves & sound, electromagnetism, optics, thermodynamics, fluids, gravitation, modern physics
- Engine: custom 2D rigid-body physics (240 steps/s), ray tracing, wave equation, Navier–Stokes fluid, kinetic gas
- Free to use; optional Google sign-in (Firebase) to save projects in the cloud

## Pages
- [Home (EN)](https://apps-educacionais.web.app/): overview
- [Início (PT)](https://apps-educacionais.web.app/pt/)
- [Inicio (ES)](https://apps-educacionais.web.app/es/)
- [All experiments](https://apps-educacionais.web.app/experiments/)
- [Extension API (PT)](https://apps-educacionais.web.app/docs/EXTENSOES.md)

## Experiments
### Mechanics
- [Free Fall and Air Resistance (Terminal Velocity)](https://apps-educacionais.web.app/experiments/free-fall-and-air-resistance-terminal-velocity): Galileo was right — but air changes everything. (app: https://apps-educacionais.web.app/app#exp=queda-livre)
- [Projectile Motion: Complementary Launch Angles](https://apps-educacionais.web.app/experiments/projectile-motion-complementary-launch-angles): 30° and 60°: same range. (app: https://apps-educacionais.web.app/app#exp=projeteis)
- [Horizontal Launch vs. Free Fall](https://apps-educacionais.web.app/experiments/horizontal-launch-vs-free-fall): Launched or dropped: both hit the floor together. (app: https://apps-educacionais.web.app/app#exp=lancamento-horizontal)
- [Inclined Plane: Friction and Rolling](https://apps-educacionais.web.app/experiments/inclined-plane-friction-and-rolling): Who slides, who sticks and who rolls. (app: https://apps-educacionais.web.app/app#exp=plano-inclinado)
- [Simple Pendulum: Period vs. Length](https://apps-educacionais.web.app/experiments/simple-pendulum-period-vs-length): The period depends only on the length. (app: https://apps-educacionais.web.app/app#exp=pendulo)
- [Double Pendulum: Deterministic Chaos](https://apps-educacionais.web.app/experiments/double-pendulum-deterministic-chaos): Two almost identical starts, completely different futures. (app: https://apps-educacionais.web.app/app#exp=pendulo-duplo)
- [Newton’s Cradle](https://apps-educacionais.web.app/experiments/newtons-cradle): Momentum and energy conservation in a chain. (app: https://apps-educacionais.web.app/app#exp=berco-newton)
- [Elastic and Inelastic Collisions](https://apps-educacionais.web.app/experiments/elastic-and-inelastic-collisions): Momentum is always conserved; kinetic energy, not always. (app: https://apps-educacionais.web.app/app#exp=colisoes)
- [Bouncing Balls: Coefficient of Restitution](https://apps-educacionais.web.app/experiments/bouncing-balls-coefficient-of-restitution): Each bounce keeps a fraction e² of the height. (app: https://apps-educacionais.web.app/app#exp=coef-restituicao)
- [Atwood Machine](https://apps-educacionais.web.app/experiments/atwood-machine): Two masses, one pulley, Newton’s second law. (app: https://apps-educacionais.web.app/app#exp=atwood)
- [Lever and Torque: Rotational Equilibrium](https://apps-educacionais.web.app/experiments/lever-and-torque-rotational-equilibrium): Double the mass at half the distance. (app: https://apps-educacionais.web.app/app#exp=alavanca)
- [Mass–Spring Oscillator (Simple Harmonic Motion)](https://apps-educacionais.web.app/experiments/mass-spring-oscillator-simple-harmonic-motion): Hooke’s law and simple harmonic motion. (app: https://apps-educacionais.web.app/app#exp=massa-mola)
- [Springs in Series and in Parallel](https://apps-educacionais.web.app/experiments/springs-in-series-and-in-parallel): Equivalent spring constant and period. (app: https://apps-educacionais.web.app/app#exp=molas-serie-paralelo)
- [Domino Chain Reaction](https://apps-educacionais.web.app/experiments/domino-chain-reaction): Ramp, energy and a chain reaction. (app: https://apps-educacionais.web.app/app#exp=domino)
- [Roller Coaster: Conservation of Mechanical Energy](https://apps-educacionais.web.app/experiments/roller-coaster-conservation-of-mechanical-energy): Energy conservation on a track drawn with the pen. (app: https://apps-educacionais.web.app/app#exp=montanha-russa)
- [Measuring g with two photogates](https://apps-educacionais.web.app/experiments/measuring-g-with-two-photogates): A classic lab bench experiment. (app: https://apps-educacionais.web.app/app#exp=medindo-g-fotoportas)

### Waves & Sound
- [Two-Source Interference in a Ripple Tank](https://apps-educacionais.web.app/experiments/two-source-interference-in-a-ripple-tank): Bright fringes of reinforcement and calm nodal lines. (app: https://apps-educacionais.web.app/app#exp=interferencia)
- [Young’s Double-Slit Experiment](https://apps-educacionais.web.app/experiments/youngs-double-slit-experiment): Plane waves through two slits. (app: https://apps-educacionais.web.app/app#exp=fenda-dupla)
- [Diffraction Grating: Many Slits, Sharper Maxima](https://apps-educacionais.web.app/experiments/diffraction-grating-many-slits-sharper-maxima): Five slits concentrate the light into narrow orders. (app: https://apps-educacionais.web.app/app#exp=rede-difracao)
- [Single-Slit Diffraction](https://apps-educacionais.web.app/experiments/single-slit-diffraction): The wave “bends” as it passes the opening. (app: https://apps-educacionais.web.app/app#exp=difracao)
- [Doppler Effect](https://apps-educacionais.web.app/experiments/doppler-effect): The siren that changes pitch. (app: https://apps-educacionais.web.app/app#exp=doppler)
- [Shock Wave and Mach Cone (Sonic Boom)](https://apps-educacionais.web.app/experiments/shock-wave-and-mach-cone-sonic-boom): Faster than its own waves. (app: https://apps-educacionais.web.app/app#exp=cone-mach)
- [Standing Waves on a String](https://apps-educacionais.web.app/experiments/standing-waves-on-a-string): Harmonics, nodes and antinodes. (app: https://apps-educacionais.web.app/app#exp=corda)
- [Harmonic Series of a Vibrating String](https://apps-educacionais.web.app/experiments/harmonic-series-of-a-vibrating-string): Fundamental, 2nd and 3rd harmonics side by side. (app: https://apps-educacionais.web.app/app#exp=harmonicos)
- [Resonance of a mass–spring oscillator](https://apps-educacionais.web.app/experiments/resonance-of-a-mass-spring-oscillator): Same system, three driving frequencies. (app: https://apps-educacionais.web.app/app#exp=ressonancia-mola)

### Electromagnetism
- [Electric Dipole: Field Lines and Equipotentials](https://apps-educacionais.web.app/experiments/electric-dipole-field-lines-and-equipotentials): Field lines and electric potential. (app: https://apps-educacionais.web.app/app#exp=dipolo)
- [Like Charges and the Electric Quadrupole](https://apps-educacionais.web.app/experiments/like-charges-and-the-electric-quadrupole): Neutral points where the field vanishes. (app: https://apps-educacionais.web.app/app#exp=quadrupolo)
- [Coulomb’s Law](https://apps-educacionais.web.app/experiments/coulombs-law): Opposites attract, likes repel. (app: https://apps-educacionais.web.app/app#exp=coulomb)
- [Charged Particles in a Magnetic Field (Lorentz Force)](https://apps-educacionais.web.app/experiments/charged-particles-in-a-magnetic-field-lorentz-force): Lorentz force and circular motion. (app: https://apps-educacionais.web.app/app#exp=ciclotron)
- [Mass Spectrometer: Separating Isotopes](https://apps-educacionais.web.app/experiments/mass-spectrometer-separating-isotopes): Same speed and charge, different masses, different radii. (app: https://apps-educacionais.web.app/app#exp=espectrometro-massa)
- [Charge Deflection Between Capacitor Plates](https://apps-educacionais.web.app/experiments/charge-deflection-between-capacitor-plates): Uniform field: parabolic path. (app: https://apps-educacionais.web.app/app#exp=capacitor)
- [Velocity Selector (Crossed E and B Fields)](https://apps-educacionais.web.app/experiments/velocity-selector-crossed-e-and-b-fields): Crossed fields let only one speed through. (app: https://apps-educacionais.web.app/app#exp=seletor)
- [Ohm’s law: series and parallel circuits](https://apps-educacionais.web.app/experiments/ohms-law-series-and-parallel-circuits): Same lamps, different brightness. (app: https://apps-educacionais.web.app/app#exp=circuitos-serie-paralelo)

### Optics
- [Law of Reflection: Plane and Concave Mirrors](https://apps-educacionais.web.app/experiments/law-of-reflection-plane-and-concave-mirrors): Angle in = angle out, and the focus of a concave mirror. (app: https://apps-educacionais.web.app/app#exp=espelhos)
- [Convex Mirror: Virtual Focus and Wide Field of View](https://apps-educacionais.web.app/experiments/convex-mirror-virtual-focus-and-wide-field-of-view): Why car side mirrors “show objects closer than they appear”. (app: https://apps-educacionais.web.app/app#exp=espelho-convexo)
- [Converging and Diverging Lenses](https://apps-educacionais.web.app/experiments/converging-and-diverging-lenses): Parallel rays, real focus and virtual focus. (app: https://apps-educacionais.web.app/app#exp=lentes)
- [Keplerian Telescope: Angular Magnification](https://apps-educacionais.web.app/experiments/keplerian-telescope-angular-magnification): Two converging lenses separated by f₁ + f₂. (app: https://apps-educacionais.web.app/app#exp=luneta-kepler)
- [Dispersion of White Light by a Prism](https://apps-educacionais.web.app/experiments/dispersion-of-white-light-by-a-prism): White light becomes a rainbow (Newton). (app: https://apps-educacionais.web.app/app#exp=prisma)
- [Rainbow in a Water Droplet](https://apps-educacionais.web.app/experiments/rainbow-in-a-water-droplet): Refraction, internal reflection and dispersion. (app: https://apps-educacionais.web.app/app#exp=arco-iris)
- [Snell’s Law and Total Internal Reflection](https://apps-educacionais.web.app/experiments/snells-law-and-total-internal-reflection): The critical angle in a glass half-cylinder. (app: https://apps-educacionais.web.app/app#exp=refracao)
- [Optical Fibre: Light Guided by Total Internal Reflection](https://apps-educacionais.web.app/experiments/optical-fibre-light-guided-by-total-internal-reflection): How the internet travels under the oceans. (app: https://apps-educacionais.web.app/app#exp=fibra-optica)

### Thermodynamics
- [Ideal Gas and Kinetic Theory](https://apps-educacionais.web.app/experiments/ideal-gas-and-kinetic-theory): Pressure as molecules hitting the walls. (app: https://apps-educacionais.web.app/app#exp=gas-ideal)
- [Molecular Speeds: Helium vs. Xenon (Maxwell–Boltzmann)](https://apps-educacionais.web.app/experiments/molecular-speeds-helium-vs-xenon-maxwell-boltzmann): Same temperature, very different speeds. (app: https://apps-educacionais.web.app/app#exp=gases-comparados)
- [Isothermal vs. Adiabatic Compression](https://apps-educacionais.web.app/experiments/isothermal-vs-adiabatic-compression): Compress two gases: only one heats up. (app: https://apps-educacionais.web.app/app#exp=compressao-adiabatica)
- [Brownian Motion and Random Walks](https://apps-educacionais.web.app/experiments/brownian-motion-and-random-walks): Visual proof that molecules exist. (app: https://apps-educacionais.web.app/app#exp=browniano)
- [Heat Conduction: Copper vs. Iron (Fourier’s Law)](https://apps-educacionais.web.app/experiments/heat-conduction-copper-vs-iron-fouriers-law): Which metal conducts heat better? (app: https://apps-educacionais.web.app/app#exp=conducao)

### Fluids
- [Buoyancy: Archimedes’ Principle](https://apps-educacionais.web.app/experiments/buoyancy-archimedes-principle): Sink or float? It depends on density. (app: https://apps-educacionais.web.app/app#exp=arquimedes)
- [Metals Floating on Mercury](https://apps-educacionais.web.app/experiments/metals-floating-on-mercury): Iron and lead float; it is all about density. (app: https://apps-educacionais.web.app/app#exp=ferro-mercurio)
- [Immiscible Liquids: Oil and Water Layers](https://apps-educacionais.web.app/experiments/immiscible-liquids-oil-and-water-layers): Objects that stop at the interface. (app: https://apps-educacionais.web.app/app#exp=densidades)
- [Hydrostatic Pressure vs. Depth (Stevin’s Law)](https://apps-educacionais.web.app/experiments/hydrostatic-pressure-vs-depth-stevins-law): Pressure grows with depth. (app: https://apps-educacionais.web.app/app#exp=stevin)
- [Wind Tunnel: Flow Around Obstacles and Vortex Shedding](https://apps-educacionais.web.app/experiments/wind-tunnel-flow-around-obstacles-and-vortex-shedding): Airflow around a cylinder and a wing-like plate. (app: https://apps-educacionais.web.app/app#exp=tunel-vento)

### Gravitation
- [Planetary Orbits and Kepler’s Third Law](https://apps-educacionais.web.app/experiments/planetary-orbits-and-keplers-third-law): Orbits, periods and a moon. (app: https://apps-educacionais.web.app/app#exp=sistema-solar)
- [Elliptical Orbits: Kepler’s First and Second Laws](https://apps-educacionais.web.app/experiments/elliptical-orbits-keplers-first-and-second-laws): Faster near the star, slower far away. (app: https://apps-educacionais.web.app/app#exp=kepler)
- [Orbital Speed and Escape Velocity](https://apps-educacionais.web.app/experiments/orbital-speed-and-escape-velocity): Circle, ellipse or escape — it depends on launch speed. (app: https://apps-educacionais.web.app/app#exp=velocidade-escape)
- [Binary Star System and the Centre of Mass](https://apps-educacionais.web.app/experiments/binary-star-system-and-the-centre-of-mass): Two stars dancing around their centre of mass. (app: https://apps-educacionais.web.app/app#exp=binaria)

### Modern Physics
- [Photoelectric Effect](https://apps-educacionais.web.app/experiments/photoelectric-effect): Einstein and light made of photons. (app: https://apps-educacionais.web.app/app#exp=fotoeletrico)
- [Radioactive Decay and Half-Life](https://apps-educacionais.web.app/experiments/radioactive-decay-and-half-life): Randomness that produces a law. (app: https://apps-educacionais.web.app/app#exp=decaimento)
- [Comparing Half-Lives of Two Isotopes](https://apps-educacionais.web.app/experiments/comparing-half-lives-of-two-isotopes): Short half-life: intense but brief activity. (app: https://apps-educacionais.web.app/app#exp=meias-vidas)
- [Time Dilation: The Light Clock (Special Relativity)](https://apps-educacionais.web.app/experiments/time-dilation-the-light-clock-special-relativity): Moving clocks run slow. (app: https://apps-educacionais.web.app/app#exp=relogio-luz)
- [Blackbody radiation and Wien’s law](https://apps-educacionais.web.app/experiments/blackbody-radiation-and-wiens-law): Why hot stars are blue and cool stars are red. (app: https://apps-educacionais.web.app/app#exp=corpo-negro-wien)

### Extensions
- [Fan and attractor: forces from an extension](https://apps-educacionais.web.app/experiments/fan-and-attractor-forces-from-an-extension): Newton’s 2nd law with custom forces. (app: https://apps-educacionais.web.app/app#exp=ext-ventilador)

## Optional
- [Full text of every experiment](https://apps-educacionais.web.app/llms-full.txt)
- [Sitemap](https://apps-educacionais.web.app/sitemap.xml)