Noun 勢い used as an adverb?


> **勢い** 地面に背中を打ちつけ、彼は顔をしかめた。

According to dictionaries, 勢い is a noun for momentum, force. In this sentence,
isn't it used like an adverb to say that he knocked him on the ground with
force?




This is indeed an uncommon adverbial usage of 勢い, but it means something
different from what you are thinking:

> ### [勢い](https://jisho.org/search/%E5%8B%A2%E3%81%84)
>
> Adverb  
>  4. naturally; necessarily

> ### [勢い](https://dictionary.goo.ne.jp/word/%E5%8B%A2%E3%81%84/)
>
> [副］その時のなりゆきで。必然的に。

So what is the previous sentence? Does "naturally" make sense?

"Hit with force" would have been 勢いよく打ち付けた, 勢いをつけて打ち付けた, etc.




This is indeed an uncommon adverbial usage of 勢い, but it means something
different from what you are thinking:

> ### [勢い](https://jisho.org/search/%E5%8B%A2%E3%81%84)
>
> Adverb  
>  4. naturally; necessarily

> ### [勢い](https://dictionary.goo.ne.jp/word/%E5%8B%A2%E3%81%84/)
>
> [副］その時のなりゆきで。必然的に。

So what is the previous sentence? Does "naturally" make sense?

"Hit with force" would have been 勢いよく打ち付けた, 勢いをつけて打ち付けた, etc.

