Collide
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.
Note:
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.