Collide
This page covers the Collide modifier of the particle system in Cinema 4D. It makes particles bounce off geometry carrying simulation tags — optionally switching group on impact, which opens up event-driven effects like splashes or triggered bursts.
You always need this Modifier if particles should collide with polygons. For this to work, the corresponding objects must have dynamic Simulate tags, such as a Collide tag, a Cloth tag or a Rigid Body tag, all of which can be found in the Object Manager under Tags/Simulation tags. Optionally, the collision of a particle can also be used to change groups.
Please note that particles themselves have no mass and therefore no force can be transferred to other dynamic objects. However, you can bind any geometry to the particles using a MoGraph Cloner object, for example, and then give these geometries dynamic properties.