In Dutch we call those verbs 'scheidbare werkwoorden' (separable verbs). They are part of a group of verbs called 'samengestelde werkwoorden' (compound verbs).
Compound verbs consist of an adverb (preposition) or adjective + verb. (‘vast + zitten’).
We distinguish two groups of compound verbs: separable verbs and inseparable verbs.
By far most compound verbs belong to the category separable verbs.
Prefixes of inseparable compound verbs are never separated from their verbs. Separable compound verbs can occur in two pieces: in the simple present and simple past, we separate the prefix from the verb.
In the past participle, the separable compound verb remains intact. (but there are exceptions)
The challenge lies in determining whether a verb is separable or inseparable.
The verb is always separable if the adverb (first part) gets the emphasis. On the other hand, if the verb gets the word accent, the verb is inseparable. (A dictionary can help you with this distinction).
I hope this will help you.