[BlueTemplar]

Particle and wave are just both incomplete ways to describe things - but for some phenomena combining both gives the best results : that is the very weird domain of quantum physics.

(Like if you're trying to predict what happens when speeds approach those of light, you have to make weird relativistic corrections stemming from the observed speed of light being the same for all observers, regardless of their relative speeds.)

If you're lucky to not be in one of those weird cases, objects as spherical things with a sharp boundary in space and using the normal composition of speeds work just fine.