Lots – hundreds at least – of small physics applets, around a wide range of topics, separated out into two semesters of college physics. Motion, thermo, EM, waves, and optics all covered. Created by Andrew Duffy.
Category: Fluids
Interactive Molecular Dynamics
Particle simulation that is great for exploring thermodynamics, or Newtonian mechanics, gas laws, etc. Created by Dan Schroeder.
Fowler’s Physics Applets
Collection of small physics simulations, many including nice explanations. Built by Michael Fowler.
JavaLab
Just an amazing trove of science simulations built by middle school teacher, DJ Lee. I’m amazed at how much is covered here.
Index of Simulations
A spreadsheet pulled together for teachers of a categorized list of hundreds (wait, thousands!) of simulations you can find online, sorted by topic. An incredible resource organized by Helen Reynolds.
The Physics Classroom
Sets of pages with lessons and interactives about a variety of physics topics.
Concord Consortium List
A collection of science interactives by Concord Consortium.
Physion
Build tons of 2D physics simulations with this free resource. Easy to check out, tons of cool stuff you can do with it. Created by Dimitris Xanthopoulos.
ScienceGameCenter
THE definitive list of science games – both digital and physical. Curated by Dr. Melanie Stegman.
Fluid Dynamics Simulation
Simulates the flow of a fluid around a barrier. Created by Dan Schroeder.