What does 勢い mean here?

Question

In Steins Gate 0 the following conversation happens between the protag おかべ and a character ひやじょう

比屋定さん… どうして ここに…
えっ？　あ いや つい勢いっていうか…
勢い？

The context is, that okabe visited his friend だる in their usual hang out place the “Future Gadget Laboratory”. While おかべ is talking with だる, ひやじょ comes out of the shower, which おかべ is very surprised by, since ひやじょう wasn’t really a regular at the place at that time, and doesn’t understand what she could be doing at the place with だる.

ひやじょう calls it 勢い, in the english translation it is translated as “impetus”.

I know that 勢 can mean that,

物事の進行や運動の力によって当然そうなるさま。自然の結果として。なりゆき上。はずみで。「みんなが賛成したので，―そうせざるをえなかった」

But it even then, I don’t really understand what she means here. In other contexts, I have seen 勢い mean doing something on impulse, or getting carried away, but how would that fit into this context?

Which meaning of 勢い is being used here, and what kind of information does it exactly convey?

Answer 1

There probably isn't a great translation, but it does mean something along the lines of "impetus" here. We don't know exactly why the character is here, but we do know that she did get here by "going along with the flow" somehow.

Let's pretend there's some kind of flow of water, then the 勢い would be the momentum of that water. If some action was done 勢いで, then it might have been carried by the momentum that the previous actions/events have already built up.

In other words, there might not have been much thought put into an action done 勢いで. In your example, she might have not actively made the decision to be there, but was instead carried there along by some past chain of actions/events.