Thread: Case Question

My Russian study book uses the following sentence:

Садитесь на пятый автобус.

I don't understand it. It seems to me that bus should be in the prepositional case since it is using "на" to mean on. What am I misunderstanding?

You are correct in saying that HA takes the locative (prepositional) case -- but that is so only when denoting a place of "rest", not movement. If there is any movement implied, you use HA with the accusative.
So, Садитесь на пятый автобус means "Board [onto -- movement] the fifth bus."
Whereas Я езжу на работу на пятом автобусе would mean "I always travel to work on ["rest"] the fifth bus."

Originally Posted by kevinfitch

My Russian study book uses the following sentence:

Садитесь на пятый автобус.

I don't understand it. It seems to me that bus should be in the prepositional case since it is using "на" to mean on. What am I misunderstanding?

Thanks a lot for you explanation. It's going to take a while for me to understand the case system.

Originally Posted by armagister

Whereas Я езжу на работу на пятом автобусе would mean "I always travel to work on ["rest"] the fifth bus."

For some reason I do not understand what "rest" is here for, but it's O.K. I don't have to know. All I wantеd to say that под пятым автобусом подразумевается автобус №5, where "5" is a rout number.

Originally Posted by kevinfitch

Thanks a lot for you explanation. It's going to take a while for me to understand the case system.

It's really not that difficult:

The prepositional, also known as locative, expresses location:

в + prepositional = in (at)
на + prepositional = on (at)

Я в библиотеке - I'm at the library
Мы живем в Москве - We live in Moscow
Он на работе - He's at work

But, the same prepositions used with the accusative case express motion:

в + accusative = (in) to
на + accusative = (on) to

Я ездил в Москву - I went to Moscow
Я хожу на работу - I walk to work

The verb Садиться literally means "to sit down", which is a motion, c.f. in English: "I sat down on (to) the chair"

There are a few other prepositions that govern the instrumental when describing a state but take the acc. for motion, ЗА for instance.