Word order: "Split up X" or "split X up"?

Question

By two simple Google searches, I find that "split up the mesh" is significantly more common than "split the mesh up", with 480,000 hits versus only 2,930.

However, when I replace "the mesh" with "it" (consider "it" as referring to the mesh) the result is reversed: "split up it" sounds weird, and it only has 848,000 hits, of which most (if not all) seem to have different meanings than what I intended for that expression (the same meaning as with "split up the mesh"), while "split it up" sounds right and has 1,560,000 hits, of which most seem to have the same meaning as I intended.

To me it seems like when I swapped "the mesh" out for "it," the correct order of the words also switched. Is this correct, and why is that in that case? Is this switching behavior common in English?

Answer 1

"Split up" is a phrasal verb, or more specifically a particle verb (see Wikipedia). In this case the particle is the word "up."

As that Wikipedia article notes, "the particle may come either before or after the object of the verb," but "when the object is a pronoun, the particle is usually placed afterwards," whereas "with nouns, it is a matter of familiar collocation or of emphasis."

Hence, since "it" is a pronoun, "split it up" would be more common, though technically "split up it" is also correct. By contrast, because "the mesh" is a noun rather than a pronoun, "split up the mesh" is fine.