Breakdown of Der Unfall geschah, weil derselbe Bus kam.
kommen
to come
der Bus
the bus
der Unfall
the accident
weil
because (subordinating)
Questions & Answers about Der Unfall geschah, weil derselbe Bus kam.
Why is it derselbe in this sentence, and how do you figure out the ending?
derselbe translates to "the exact same". Since Bus is a masculine noun and is the subject of the second half of the sentence, it needs the masculine nominative form. Think of it as two parts glued together: the definite article (der) and the word selbe taking a standard weak adjective ending (-e). Written together, you get derselbe.
Would it be wrong to say der gleiche Bus instead of derselbe Bus?
Technically, yes! derselbe means it was the exact same physical bus (for example, the exact vehicle that was involved in a previous incident). If you used der gleiche, it would mean a bus of the same type, model, or route, but a different physical vehicle. Native speakers sometimes mix these up in casual speech, but the distinction is important in written German.
geschah is the simple past of geschehen (to happen). Why use this instead of the more common passieren?
Both words mean "to happen", but geschehen sounds a bit more formal or serious. You will often see it used in news reports, police statements, or literature when talking about accidents or historic events. In casual conversation, you would be much more likely to hear the perfect tense with passieren, such as Der Unfall ist passiert.
Just as a quick refresher, why does kam end up at the very end of the sentence?