# How to simulate static vs kinetic friction?

Rigid Body simulation allows setting bounciness and friction. Is there any simple way to set friction and bounciness to match real world objects? Real world objects have different Friction Coefficients for static (non-sliding) and kinetic (sliding) contacts which Blender doesn't seem to support. In addition, Blender Rigid Body simulation is (according to name) about rigid bodies only so even though you can simulate a bouncing tennis ball by setting suitable bounciness, it's not physically correct simulation.

For example, let's say we have three 0.1 m x 1.0 m x 1.0 m objects (squashed cubes) made out of wood, steel and styrofoam. How to simulate those? In real world, steel would't easily slide over styrofoam but it would slide over wood.

Numerically, static friction (and the transition between static and dynamic friction) is extremely difficult to model, because of the abrupt jump and the directional ambiguity at the threshold between moving and non-moving. In general, most friction force models therefore actually set the force to zero around the point of zero velocity!

Keep in mind that the the Blender physics engine is not intended for scientific or engineering purposes. It is rather meant to be comparatively simple and fast.

Therefore, you may have to use creative fakery for the feeling of physical accuracy. Maybe simulate the objects (if necessary, separately), bake their trajectories to keyframe and tweak manually. Maybe you can also achieve more impressive results with softbody simulation instead of rigid body simulation.

Or use a dedicated multibody-simulation software (there are free packages out there, like https://projectchrono.org/), but those are way more complex than blender.