Why do you even assume that they will find a common language under stress.
They will communicate with gestures. Just banal gestures. In a closed space.
Terms of the question are not defined. 8)
The decision depends on the set of languages, gender, age and character of people.
Languages belong to the same language group or to different (Germanic, Romance, Slavic ... about Asian and African generally keep quiet)? Which group is the strongest?
And I'll tell you a funny fact, which was the witness himself. If deaf children are locked in a confined space for a week, then in a day - the latter will be able to communicate with each other with gestures quite calmly. And no problem at all!
The part will be explained in "surzhik", created ad hoc by those of the group members, whose languages belong to the same language family or contain a number of borrowed words (for example, from Latin and the ancients like brother-brother). Another part of the people in the group will be explained by gestures and drawings, but understand "surzhik". By the way, many signals can also be transmitted by interjections, here there are more similarities in languages, tk. they have a significant emotional coloring.
They will begin to understand each other at a primitive level rather quickly. The situation is not unique, there are many examples in reality. Some kind of pidgin will be born, such a common simplified language. Someone, roughly speaking, points to bread and calls it "bread", the rest catch up with what he means and repeat: "kleeb", "ihlep", "haleip" ... As a result, behind the concept of "bread" in Some kind of transitional form is fixed in this community, which is more or less convenient for everyone to pronounce, for example, "helep". Done, there is one word in the new language. According to the same scheme, several tens, or even hundreds, of words will be formed to describe the surrounding things, phenomena, basic adjectives (hot, white ...) and verbs (eat, carry, sleep ...). This will already allow maintaining basic communication, although this is still a long way for poetry and scientific disputes.
Syntax, morphology, pronunciation will be extremely simplified, words will be pulled from different languages, depending on how convenient it will be for everyone to pronounce, will go through a meat grinder and in a distorted-averaged form will be included in the vocabulary of the local common language .
And here is how it looks in reality. Examples of phrases from Russenorsk, a mixed language used by Norwegians and Russians for basic contacts.
Moja på tvoja. - I speak your [language].
Kak sprek? Moje niet forsto. - What are you saying? I don't understand you.
Å råbbåte - Work.
Klæba - Bread.
Drasvi, gammel god venn på moja! Kor ju stannom på gammel ras? - Hello, my good old friend! How were you doing yesterday?
Ju spræk på moja kantor kom - You said that you would come to my office.
Moja på ander kantor, nokka vin drikkom, så lite pjan kom - I was in another office, drank a little wine, and then got a little drunk.
Tvoja fisk kopom? - Will you buy fish?
Saika kopom i på Arkangelsk på gaf spaserom - I will buy pollock and swim to Arkhangelsk.
Kak pris? Mangeli kosta? - What price? How much does it cost?
En voga mokka, så galanna voga treska - One flour for half a load of cod.
Eta grot dyr. Værsegod, på minder prodaj! - It is very expensive. Please sell for less!
Considering that all 10 are monolingual, and not from the same language family, it will be difficult to agree.
It will take a long time to come to a common language, gestures will dominate.
Then a wild pidgin will be born, the basis of which will be common, even remotely words in languages, but it will be extremely primitive. One way or another, everyone will become polyglot, in one way or another. In a few years, everyone will know a couple dozen words in all 10 languages. How long these people will be able to understand each other well is a subjective question. One thing is for sure - in the first generation a "common" language will not be born, it may take 3, maybe 4 generations. Perhaps there will be no common, these 10 languages will merge into 3-4, according to the principle of closest proximity, and the common pidgin will be the one that appeared at the beginning, only in a more advanced version.
If they stay in the same meta for a long time (sooooo long), then they can develop their own language, or rather, pidgin. Pidgin represents himself as a vicious child, more often than not, of two languages, which are simplified to the point of indecency. There is no grammar, the vocabulary of the language is very poor and, most often, combines either words from interacting languages, or such Frankenstein monsters - words that appeared as a result of morphemes of different languages joining each other.
For example, when Russia traded with Norway in the 17th century, naturally, no one used English. They had their own pidgin there based on Russian and Norwegian.
And if they give birth to children in this closed space, then it will already be a Creole. For example, the language that all of my classmates giggled at in their green first year, Tok-pisin. Originally a pidgin for trade, it is now quite an official language in Papua New Guinea.
And it seems to me that it will be easier for people to learn the basic actions and things that everyone shows in their own language. It's easier than creating a new language, or having everyone come to the same language. Sign language + a little understanding of each language, this is what I think will happen
I really liked the idea proposed by Maxim in the first paragraph, that if there are at least two representatives of the Romanesque family (or any other language family), then it will be easier for them to agree among themselves, these guys will begin and form the core of a new language, and for others will have to "pull up". Perhaps even several language clusters are formed. Further, according to the principle of the nearest neighbor, they will have to unite with each other, learning what is what. Each will slightly simplify their own language, and difficult to pronounce sounds will be leveled. At first, the language will be extremely utilitarian, with almost no grammar, just so that group actions (what to do, where and when) can be coordinated.
This symbiosis will clearly resemble the Romance family of languages. Most of the popular languages (English, German, French, Spanish, etc.) come from the Romano-Germanic family (read "Latin"). These languages have a common ancestor, many words, letters and sounds are similar. Yes, please, even the alphabet is similar. So this language will definitely resemble Latin. At least lexically.
What happens if there is not a single native speaker from this family in the room? For example, a Russian, a representative of some African tribe, a Chinese and a Chukchi will gather in a room (as if in some kind of anecdote). And here again the Romance family comes into play, or rather good old English.
Have you ever wondered how many people speak English? For about 25-30% of the world's population, English is their native language. How many people teach him? Yes, almost every first inhabitant of the Earth knows at least one English word, and every second will be able to make a more or less meaningful sentence.
So I'm almost sure that the language will be as close as possible to English, the Latin alphabet will be used and everyone will love hamburgers and soda.
If we assume their long-term interaction (several years, for example), and take into account that none of the languages learned by one person is repeated by other members of this group, then the language of the most charismatic representative can become a common language for all. The one who takes the lead and initiates communication in his language. Just a guess.
It seems like I was put in exactly this place on the integration course, where we all learn German. So from personal experience I can say that there are two options: English, which may not be native to anyone, but can become a base for communication and sign language (oh yes, believe me, it should not be underestimated). If we talk about a closed space and in terms of information, and exclude Google translate, then for especially difficult cases there is drawing. Recently, using a drawing, I explained to a girl from Myanmar who a flea is. We figured it out pretty quickly :)