Algodoo

HOW IT WORKS
The red circles are attracted to each other and the cog there attached too.

The hinges holding them together allow for this phenomenon. If you change the cogs collision layer the engine will not function. If you fix the red circles to the cog it will not function.

Works with gravity on or off.
Works with only one engine in a scene
(Press Delete to remove all but one engine)
Can be connected together for more power.

CONTROLS
Tap Left or Right arrow keys to start up the engine.
Up arrow to toggle the clutch.
Down arrow to brake.

Have fun

EDIT: If you increase the Density of the cog to 100.0 kg/m2, it can reach speeds of 166 m/s