Quiz!! Do you think it is right? I saw this questions. And, I found it very interesting.
"okay so う at the beginning makes the “u” sound but if it’s at the end it makes an “o” sound, is that right?"
Okay, here is example and answer.
ex. おはようと言う/Ohayou to iu
おはよう met this criteria. It ends with う, but pronounce お. Instead of Ohayou native pronounce Ohayō, they'd even write it オハヨー in Katakana. That signifies this is a long vowel.
いう also met this criteria, which ends with う. However, no one pronounce it イオ. Why? The secret is "what vowel precedes う."
おはよう, prior to う, よyo appears. If vowel おO precedes う, they're going to be long vowel, おおOO, like おはよー.
いう, prior to う, いi appears. If any sounds besides お precedes, it pronounce as it is. いう
Btw, if prior to う, うu appears, then it sure becomes long vowels too, which is UU, as well as other long vowels.
*actually, とおい is the exception on the rule of Japanese writing. It should be written literally, not とうい. Have you noticed it?