浮力
ふりょく · furyoku · JLPT N1 · noun
buoyancy
浮 — water radical 氵 + 孚 (phonetic, 'hatch/trust')
浮 is a semantic-phonetic compound. The water radical 氵 gives the meaning 'water,' while 孚 supplies the sound and originally depicted a bird hatching an egg. Together they convey something resting on water, hence 'to float.'
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'.