Step is an interactive physical simulator. It allows you to explore the physical world through simulations.

Features

• Classical mechanical simulation in two dimensions
• Particles, springs with dumping, gravitational and coulomb forces
• Rigid bodies
• Collision detection (currently only discrete) and handling
• Soft (deformable) bodies simulated as user-editable particles-springs system, sound waves
• Molecular dynamics (currently using Lennard-Jones potential): gas and liquid, condensation and evaporation, calculation of macroscopic quantities and their variances
• Units conversion and expression calculation: you can enter something like "(2 days + 3 hours) * 80 km/h" and it will be accepted as distance value (requires libqalculate)
• Errors calculation and propagation: you can enter values like "1.3 ± 0.2" for any property and errors for all dependent properties will be calculated using statistical formulas
• Solver error estimation: errors introduced by the solver is calculated and added to user-entered errors
• Several different solvers: up to 8th order, explicit and implicit, with or without adaptive timestep (most of the solvers require GSL library)
• Controller tool to easily control properties during simulation (even with custom keyboard shortcuts)
• Tools to visualize results: graph, meter, tracer
• Context information for all objects, integrated wikipedia browser
• Collection of example experiments, more can be downloaded with KNewStuff2
• Integrated tutorials