That made me realize how tiny and powerless I am.
I got a Yu-Gi-Oh! trading card called "Proof of Powerlessness."
The police were powerless to do anything about the stalker and in the end she was killed.
When your power is nothing you are powerless.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. You also can know that 力 uses its りょく reading because when you tried to pick up a tiny rock (りょく) you couldn't, because you were powerless.