Laura C. answered 05/19/22
Learn German/ESL with a Linguist - Patient and Kind Trilingual Tutor
So, basically, "to drop" is semantically different from "to drop in," and syntactically "in the bucket" is separate from "drop" whereas "drop in" is considered a set phrase. Let me explain.
Let's start by defining "drop in." "to drop in" has a set definition: "to stop by" or "to make a visit." If you were tempted to define it as "to deposit [something] to the inside of something," let me explain the difference. (Note the vagueness of that definition, with the "something's" in it, it seems incomplete - this is because the prepositional phrase has no object.)
Now, let's look at "to drop" by analyzing the sentence you provided: "drop the money" and "in the bucket" - these are two separate syntactic elements. "drop the money" is one syntactic phrase, a transitive verb ("drop,") and a direct object ("the money") and "in the bucket is a second syntactic phrase, a prepositional phrase (a preposition "in" + an object, "the bucket").
You can't use "drop in" (the phrasal verb" in this sentence because it's an intransitive verb, so you can say things like "John dropped in today to give me some money," "I need to drop in sometime to see you, it's been so long," or "I just wanted to drop in really quickly to pick up the books I left at your house the other day." But you can't say "The money dropped in the bucket." Note that the correct examples feature "drop in" followed by an adverb or infinitive phrase, whereas the incorrect sentence uses the preposition + noun phrase structure of a prepositional phrase. This is key.
(Note: for the record, if you were describing a situation where there was some money lying on a ledge above a bucket and it fell in, "into" is more appropriate, because you're describing a situation with movement.)
- to move in - "moving in" is the process of bringing your belongings to a new home to prepare to stay there. For example, "There are some new neighbors moving in. We should introduce ourselves." Or, "I can't hang out tomorrow. I'm finally moving in to my new apartment." If you wanted to use the verb + preposition without the idiomatic meaning, you could say, "For this dance, you have to move your feet in a diagonal direction and follow with your feet." Note that you can separate "in" from "move" and put "your feet" in the middle. That's not possible when you're using the phrase as an idiom (except in an extreme example).
- to run into - "running into" a person or thing means to encounter them by chance. For example, "What luck that I ran into you today, I was going to call you to figure some things out about the party. Or "I ran into some trouble at the office on Thursday and had to stay late." But instead of using this idiomatic meaning, you could use it literally, such as with the following example sentences: "I ran into a tree with my bike and damaged the frame." or, "I wasn't looking and I ran into a light pole this morning. I feel pretty stupid."