When a vocab word is a single kanji all alone with no okurigana (hiragana attached to the kanji), it usually uses the kun'yomi reading. You didn't learn the kun'yomi reading with the kanji, so for this vocab word, we'll use a mnemonic.
The most powerful man in the world. All his power came from his cheek (ちから). Imagine him blowing up his cheek like a giant balloon, then unleashing his power on you. Thwap thwap thwap thwap.
I’m hungry and losing strength.
That American woman has the power to move Mt. Fuji.
My mom is more powerful than the rest of my family put together.