力強い
ちからづよい · chikaraduyoi · JLPT N2 · i-adj
strong
💪 力 (chikara, power) + 強い (tsuyoi, strong) = power + strong: strong in power
力強い is built from 力 (force, power) and 強い (strong). Read chikara as 'power' and tsuyoi as 'strong'; together they mean powerful, vigorous, full of strength.
力 — pictograph of a plow or arm muscle
力 originated as a pictograph of an ancient plow, the main tool requiring physical exertion in early agriculture. Some scholars also see it as a flexed arm showing muscle. From this concrete image it broadened to mean 'strength, power, force, effort'.