Please, restrict your answers to etymological info. I browsed some other questions and found some good info here: Is it correct to change the common structure in these phrasal verbs?, which is more of a disambiguation question, but it may help answerers on this question. Specifically, this idea: 'The preposition is fused to the verb to create a new, figurative meaning.'
I'm wondering why some verbs have a preposition dangling after the object. I thought it was perhaps because it's expected to connect to an indirect object, but then I found myself adding additional prepositions that sometimes obviate the need for the first one (some examples in square brackets). Example:
I put some burgers on. Cooked them up. Turned the heat down [to low]. Called Nancy up [on the phone]. Asked her if she could come down [to my house]. She freaked out. Said she was down [to come]. I passed out. When I came to, she was looking me over.
She asked, "What knocked you out?"
"You and I being on," I replied.
"Let's chow down," she suggested – but I cautioned, "Wait up. Maybe the burgers are burnt up."
She said, "No. You'd turned the heat down," and pulled two plates out. We scarfed the burgers down and funned around for two more hours before turning in.
I'm basically wondering how words like these developed.