Free online physics simulators
PegFlux simulators turn a single physical idea into something you can manipulate immediately. The Pendulum Simulator focuses on repeating motion and energy. Collision Lab makes momentum transfer visible. Orbit Sling shows how sideways speed and gravity can create curved orbital paths, while Physics Sandbox gives you a small playground for changing gravity and building collision chains.
Every simulator runs directly in a modern browser with no signup or download. They are deliberately smaller than a full engineering tool: the aim is to make the important behavior easy to see, replay and compare on a phone or desktop.
Games, experiments and learning
These pages sit between an arcade game and an educational simulation. There is a simple score or challenge to encourage replay, but the useful part is observing how the system changes. Try repeating one setup, then adjust a single variable—launch radius, push direction, gravity level or impact angle—and compare the next result.
Where to start
Choose Pendulum Simulator for the clearest one-variable experiment. Collision Lab is best for fast chain reactions. Orbit Sling is more exploratory because a small change in position can produce a very different path. Physics Sandbox is the open-ended option when you want to add many objects and switch gravity while everything is moving.
For more arcade-style physics, continue to Gravity Drop, Gravity Maze or the main Physics Games category.
Small simulations, fast comparisons
A full physics engine can expose dozens of parameters, which is useful for engineering but often makes a quick experiment harder to read. PegFlux keeps each simulator narrow on purpose. One page focuses on periodic motion, another on impact and momentum, another on orbital balance, and the sandbox lets you combine gravity with repeated collisions. That makes it easier to change one thing, observe the result and immediately try again.