tear open sth，tear sth open都可以
，都是宾补，表示动作对宾语作用后的结果或者状态。
至于为什么用tear open sth这类更多，
我觉得可能由于：
ear sth open，当sth很长，比如带一个定语从句，一般都会把open提前面，要不然tear those bags that you just bought yesterday in the super market open就不符合英语重点内容先表达的基本用法，open提前，渐渐的tear open sth被当成了类似于及物动词的词组。
长宾语后置的情况很多，这是其中一种用法。

很多动词都加形容词，描述 结果

A resultant adjective (also known as a resultative adjective) is an adjective that describes the state or condition of a noun as the result of an action. In other words, it indicates what happens to the noun after a specific action has been performed.
For example, in the phrase "tear it open":
"Tear" is the action verb.
"It" is the direct object of the verb "tear."
"Open" is the resultant adjective, describing the state of "it" after the tearing action. The object becomes "open" as a result of being torn.

open 可以做及物动词、不及物动词和形容词。