Prepositions end up at the end of sentences that are using phrasal verbs, that is a verb plus a preposition where the preposition isn't starting a prepositional phrase.  Phrasal verbs are perfectly okay and are very common in Germanic languages, less common in something like Latin.  

[English has several registers--levels of formality-- and phrasal verbs are not preferred in formal English][1].


  [1]: http://www.englishonline.org.cn/en/exams-work/ielts-preparation-articles/article-eleven