Implementations in Unity of the YouTube channel Ten Minute Physics.
Simulate a bouncy cannon ball.
Simulate billiard balls with different size and mass. Watch this YouTube video for examples:
Simulate a pinball game.
Simulate beads attached to a circular wire.
Simulate the chaotic behavior of pendulums with as many arms as you want and where each arm can have different mass. With many arms you get a rope or hair! Watch these YouTube videos for examples:
Catch and throw a ball with your mouse.
Simple unbreakable soft body bunny physics. You can flatten it and throw it around with your mouse.
Find overlaps among thousands of objects blazing fast. Implements a version of the Spatial Partitioning design pattern called "Spatial Hashing" which is really useful if you have an unbounded grid.
Is not optimizing the code from #11, but is showing how you can use a more detailed mesh and make that faster. You use two meshes: one with fewer triangles that is tetrahedralized, and one with more triangles, and then they interract during the simulation.
Implemetation of an algorithm that splits a mesh into tetrahedrons. Will be available here when finished: Open source Computational Geometry library
Basic cloth simulation.
Spoiler: It's just the simulation part that's 200 lines of code. You need a few more lines of code to set it up, display it on screen, etc. Watch this YouTube video for examples:
Simulate a swimming pool with balls.
Bonus implementations related to the code above.
Simulation of planetary orbits based on this famous unsolved problem (https://en.wikipedia.org/wiki/Three-body_problem). Watch this YouTube video for examples: