Use of phrasal verbs

Question

I have questions regarding phrasal verbs. Their usage isn't so clear to me:

• What is the difference for example between "write something" and "write something up"?
• In the previous sample why "something" must be placed before "up"?

Any article on this subject would be very helpful for me!

Thanks very much

Answer 1

Phrasal verbs are often idiomatic so there is a fair bit of inconsistency around their use.

There's a really good Wikipedia page about their use here

In your examples

write something

Straightforward - the act of writing something...

The phrasal version follows the normal subject - verb - object pattern

Peter (subject) will write up (phrasal verb) a report (object)

The specific use in the question of

write something up

muddies the waters a bit as it is grammatically correct as it stands.

I'm staying late in the office because I have to write something up

Here the object is deliberately non-specific