功率
gōng lǜ · HSK 7
power
⚡ 功 = work/merit + 率 = rate; literally 'work-rate' = power output
功 means achievement or work done (as in 成功 success). 率 means rate or ratio (as in 效率 efficiency). Together 功率 is the rate at which work is done — the physics term for power.
功 — work 工 (phonetic) + strength 力 (semantic)
功 is a semantic-phonetic compound. The right side 力 (strength, a pictograph of a plow or flexed arm) gives the meaning, while 工 (work, originally a carpenter's square) supplies the sound. Together they convey effort applied to work — hence 'achievement, merit, accomplishment.'
率 — twisted silk threads with droplets, plus 十
率 originally pictured a net or twisted bundle of silk cords with water droplets shaking off, suggesting something being led or pulled along. From 'leading a rope' it extended to 'lead, command' (shuài) and to 'rate, ratio' (lǜ), as in a fixed proportion. The two readings share this core image of a guiding measure.