Questions & Answers about Очередь у кассы тянется до входа.
Why is касса in the form кассы?
Because the preposition у (meaning by / near / at) normally requires the genitive case.
So у кассы = near the cash register / at the checkout.
Base form: касса (nominative) → genitive singular: кассы.
Why is вход in the form входа?
Because the preposition до (meaning up to / as far as) also requires the genitive case.
So до входа = up to the entrance.
Base form: вход (nominative) → genitive singular: входа.
What does у кассы mean exactly, and how is it different from в кассе or к кассе?
- у кассы = by/next to the cash register (location near something)
- в кассе = in the cash register / in the cashier’s office (inside; usually not what you want here)
- к кассе = toward the cash register (direction; movement destination)
So for a line that is physically located near the register, у кассы is the natural choice.