"Do they have a bicycle?"
Translation:У них есть велосипед?
I wrote the same, "У них велосипед" was taught to me in Rosetta Stone, I've reported it. If we are wrong, please explain us.
Is there a shorter word for велосипед, like how English has bike for bicycle?
Велик, вел, байк are used informally. But long word велосипед is still very popular too.
What do the "у ... естъ" parts of "у них естъ" translate to in English (if anything)? Does "них" also mean "they" outside of this context?
Some languages (Russian included) show possession by saying that X is at/by/of/on Y to mean "Y owns/possesses/has X".
Here, у is a preposition that generally indicates proximity (so it can mean "with", "at", "on", "upon" etc.), них means "them" (prepositional form of the word "they"), and есть means "there is." Thus, this sentence could literally be translated "Upon them there is a bicycle", which just means "They have a bicycle."
Why the prepositional form, not the genitive? Is it because of the question format? Could "They have a bicycle" be translated as "У их есть велосипед"
Edit: A better explanation (from what I previously wrote) is because "у них" is a prepositional phrase: the bike is "upon them," so to speak. "Their" is an adjective, strictly speaking, and possessive adjectives are not used in Russian, at least not in the same way they are in English.
I think that's a better reply than "That's just how Russian does it."
Is the Russian word "велосипед" related to the English word "velocity" or is that just my brain finding an interesting way to remember the word (It's basically a cognate, but I was writing "велосиклед" for a bit there...couldn't figure out why I was wrong)
When bicycles were first invented "velocipede" was the generic term (including in English) for vehicles propelled by pedalling. It derives from the Latin for "speed" + Latin for "foot". As design settled on the 2-wheeled version (bicycle as opposed to the unicycle or the tricycle) English vernacular picked on specifying the wheel arrangement as the normal way of referring to your velocipede.
In short: yes, it directly relates to "velocity", from the same Latin word.
This thing marks you wrong for not knowinf how to spell russian words, in english