Elastic Collision
2D elastic collisions conserving both momentum and kinetic energy. Balls bounce off walls and each other with perfectly elastic interactions. Watch total energy and momentum remain constant throughout.
About this lab
An elastic collision is one in which kinetic energy is conserved in addition to momentum. For two balls colliding, the collision resolves along the line connecting their centers. The velocity components along this normal are exchanged in a mass-weighted fashion; the tangential components are unaffected. The result is that two equal-mass balls exchange velocities completely, while a light ball bouncing off a heavy stationary one reverses direction.
Real billiard balls, gas molecules in an ideal gas, and atomic-scale scattering events all approximate elastic collisions to varying degrees. The Maxwell-Boltzmann speed distribution — the statistical distribution of molecular speeds in an ideal gas — emerges from exactly this kind of elastic scattering over many collisions. This simulation uses continuous-time collision detection to prevent overlap and ensure energy conservation to numerical precision.