Why do we say “open” and “closed”? Why is one in present tense and the other in past tense?

Question

Edit: to clarify, I mean when shops have a sign that says “open” versus “closed”. Why is it not “opened/closed” or “open/close”?

In: Other

Answer 1

They are both adjectives describing a thing. “Open” can be used as an adjective. “Closed” meaning covered or shut is the adjective form of the word “close.”