I looked up the Oxford dictionary, it says that up could mean "into pieces/apart". I want to know why. What do you native speakers feel when you say up in "tear up" or "rip up"?
There is an example sentence in Oxford dictionary:
They've had the road up to lay some pipes.
As far as I could understand, up means upward. How could it mean "into pieces"? I don't understand.
The up particle in the verb tear up doesn't mean 'into pieces'; that's what it means with tear, because of what tear means. Note that, because English orthography, there are two verbs tear, pronounced differently, one transitive, one intransitive, with completely unrelated meanings. And both of them have phrasal verbs with up. The same up.
This particle up -- there are others, like the up's in look up, throw up, or stand up -- appears with many phrasal verbs in a completive sense. It's one way to extend the sense of a verb. Phrasal verbs with this particle, like burn up, drink up, eat up, use up, read up, write up, and finish up, all refer to some event or activity going to completion, whatever 'completion' is in each particular case.
So if you're ripping something up, it ends up in shreds. But if your eyes are filling up with tears, you feel like crying. Both of these could be spelled as tearing up. Same up, different tear; but no shreds involved with crying.
Something that burns up burns completely; a house that burns down burns to the ground. Consequently the house burned up means the house burned down, a fact which has not escaped the attention of most six-year-old English speakers.
There are literally thousands of English phrasal verbs with up (because there are many thousands of English verbs, and most of them have several phrasal verbs). Many have the completive sense of up.
When you're thinking of a verb, think about its phrasal verbs, to see what it can mean in context. Like the variegated prepositions and complements that verbs take, the particles they form phrasal verbs with are part of the meaning of a verb. Each one is a puzzle piece, which fits some, and not other, contexts.
"Up" in this case is an adverb that gives the preceding verb a sense of finality. As in done. Finished. Completed.
Eat up: finish eating.
Shut up: keep completely silent starting right now.
Wake up: stop sleeping and be completely awake.
Look at the definition No. 16:
Merriam Webster's definition of "tear up" is:
to damage, remove, or effect an opening in
with the example
tore up the street to lay a new water main
MW also says that "tear up" with this meaning is first recorded from 1620 so the usage is quite old.
Also the Oxford Advanced Learners' dictionary defines "tear up" as a phrasal verb with a very similar meaning.
This does not mean that "up" can mean "into pieces" in any sense, it only means that the "tear" and "up" used together can mean "to rip into small pieces".
As Ricky's answer says the word "up" is used to give the verb a sense of completeness.
There are a number of these phrasal verbs with "up" used in this way, they include: "crumple up" (meaning to crush) "bundle up" (meaning, in British use at least, to tie up into a bundle), and "zip up" (meaning to close an item of clothing or a bag using a zip fastener). In each case there is a sense of completeness and finality.
I suspect, but have no proof for my suspicion, that the origin of this usage lies in the fact that the items which are being torn, crumpled and bundled (zip fasteners are much later than the 17C) are actually raised from their resting places in order for the action to be taken. This is particularly true of items which are "bundled up" as the resulting bundle sits much higher than the individual items before they are brought together.
In the case of "having the road up" the road surface and part of the substructure is physically raised when the operation is carried out so there is no mystery there. The same is true of "digging up a bush" or "digging up buried treasure". Having said that the sense of completeness is also present.
Okay, I was a poor English student, but I have been a native US English speaker for 63 years.
What do you native speakers feel when you say "up" in "tear up" or "rip up"?
When you tear something, you have to start somewhere right? Tear up or rip up, is from the bottom up, probably to do, originally, with ensuring that you tear through whatever signature may be at the bottom of a contract, for instance. I've always suspected the origins to do with medieval contract law. The bottom of the sheet is usually closest to you on the desk, and that is where the signatures are. Any sense of finality may also derive from that.
Tear down is from the top down and is commonly used where you have a complex assembly where it would be difficult or impossible to disassemble from the bottom up, but where you might be referring to "ripping through something", not used a lot in reference to paper, but tearing down a snow covered mountain has everything to do with tearing down, ripping and carving through the snow.
Time is up, likely derives from the desk candles, with hour marks on them, used to work after sunset, prior to electricity (I used them in my forts when camping out as a child). You were out of time when the flame converted your candle to the smoke that invariable rose up out of the flame. The same was true of oil lamps, but I am not aware of any that had time marks on them.
Normally we sleep near the horizontal plane, so waking up, involves sitting or standing up. Here there's also a weak association with finality/time, as sleep time ends when you are up.
So today, which-ever direction in which you physically tear any paper, there's finality to it in the sense that you are done with that. You have ripped it up. It doesn't make sense to tear or rip it down, because we use those phrases to describe a more complex process that has less finality to it. When you tear-down an engine, you can always put it back together again (with or without a few extra parts laying around when you're done).
