Introduction
Physion is a free, browser-based 2D physics simulator that lets you design and run interactive physics experiments without installing any software. Think of it as a CAD-style drawing tool combined with a real-time physics engine: you add shapes, connect them with joints, apply forces, and hit play, entirely inside your web browser.
Whether you are a teacher building classroom demonstrations, a student exploring physics concepts, or just someone who enjoys building mechanical contraptions, Physion gives you the tools to bring your ideas to life.
Key Features
- Rich shape library: circles, rectangles, capsules, polygons, regular polygons, text bodies, polylines, spirals, and gears
- Physics joints: revolute, weld, distance, wheel joints, and springs for building mechanisms
- Liquid & particle simulation: fluid bodies (LiquidFun) and particle emitters for soft-body and liquid effects
- JavaScript scripting: attach Node Scripts to any object for custom collision responses, animations, and game logic
- Assets library: import images, fonts, and scripts from the web or Physion's built-in asset collection
- Boolean operations: combine, subtract, and intersect shapes with union, difference, and intersection tools
- Laser raycast: add lasers that bounce off surfaces and trigger script callbacks
- Scene sharing: save your scenes, make them public, and share them with a link
Educational Simulations
Physion is widely used in classrooms to make abstract physics concepts tangible through interactive visualization. Topics you can demonstrate include:
- Newton's Laws of Motion
- Hooke's Law and spring oscillations
- Kinematics and projectile motion
- Energy conservation and collisions
- Pendulums, gear trains, and mechanical advantage
- Fluid dynamics and buoyancy
Students can manipulate parameters in real time and immediately observe how the simulation responds, deepening intuitive understanding far beyond static diagrams.
Simulations For Fun
Beyond the classroom, Physion is a playground for creative builders. Popular uses include:
- Rube Goldberg machines: chain unpredictable cause-and-effect sequences
- Marble runs and pinball tables: design tracks, bumpers, and launchers
- Ragdoll physics: drop articulated figures into obstacles
- Particle art: combine liquid simulation and tracers for generative visuals
- Mechanical contraptions: gears, conveyor belts, and motors all in one scene
Getting Started
- Open Physion in your browser and create a new scene via File → New File.
- Use the Design Toolbar to add shapes to the canvas.
- Connect shapes with joints from the same toolbar.
- Press Space (or the play button) to start the simulation.
- Use the Property Editor to tweak any object's physics properties.
No account is required to experiment. Create a free account to save and share your scenes.
Continuous Improvement
Physion is actively developed and new features are added regularly. If you have ideas, suggestions, or feature requests, join the Discord community and let us know.