Translation of "wow" into Japanese

Wow, you got your hair cut short. For a moment, I didn't recognize you!

わあ、ショートカットにしたんだ。一瞬、誰だか分らなかったよ。

Wow, that's so big.

わぁ、すごい大きい。

Wow, I saw a car painted with anime characters for real. I think it's the first time.

うわ、痛車をリアルに見たの、初めてかも。

and he picks up the phone, and he says, "Wow, mom, how are you? Where are you?"

彼は「やあママ 元気? 今どこにいるの?」と言うのです

Wow, it's hot today.

うわー、今日は暑いね。