Learn Hardcore Norwegian: Bøkene faller av bordet når vinden er sterk. - The books fall off the table when the wind is strong.

In Norwegian Bokmål the definite article is not a separate word but a suffix attached to the noun. The ending you use depends on gender (masculine/feminine/neuter) and number (singular/plural):

• bøker (indefinite plural “books”) → bøkene (definite plural “the books”)
• et bord (indefinite singular neuter “a table”) → bordet (definite singular “the table”)

So whenever you see -en, -et or -ene at the end of a noun, it’s signalling “the.”

What role does av play in faller av? Can I leave it out or use another preposition?

av is the preposition that, together with faller, creates the meaning “fall off.”

falle alone just means “to fall.”
falle av specifically means “to fall off.”

If you drop av, you lose the “off” part of the meaning. You cannot replace it with på (which means “on”) without reversing the sense. Colloquially you might hear ramle av or blåse av, but av remains the same core preposition for “off.”

Why is the verb faller in the present tense? Does this describe a single event or something else?

The present tense in Norwegian often covers:

A general truth or fact
A habitual or repeated action
A future plan (less relevant here)

In this sentence, faller indicates a habitual/general situation: “Whenever the wind is strong, the books fall off the table.” If you wanted to narrate a single past event, you’d switch to past tense:
Bøkene falt av bordet da vinden var sterk.

Why is the clause når vinden er sterk placed at the end? Can I move it to the beginning?

Norwegian allows time clauses (introduced by når) to appear at the beginning or end of a main clause. The only thing to watch is the V2 (verb‐second) word order:

End position (very common):
Bøkene faller av bordet når vinden er sterk.

Front position (also correct, but more formal/literary):
Når vinden er sterk, faller bøkene av bordet.

In either case, the finite verb (faller) remains in the second position of the main clause.

What is the difference between når and da when translating “when”? Why is når used here?

• når is used for general, repeated, or future events (“whenever,” “when … always”).
• da is used for specific events in the past (“when” as in “back then”).

Since our sentence describes a recurring situation (“whenever the wind is strong”), we use når.

Why is the adjective sterk not sterkt, given that vind is a neuter noun?

In Norwegian Bokmål adjectives agree with gender, number, and definiteness only when they’re attributive (i.e., placed directly before a noun). Here, sterk is in a predicative position (after er), and predicative adjectives are not inflected.

Attributive examples:

en sterk vind (masculine/feminine singular)
et sterkt hus (neuter singular)
store bøker (plural)

Predicative example:

Vinden er sterk. (always sterk, regardless of gender)