加快
jiākuài · HSK 3
speed up
⏩ 加 (add) + 快 (fast) = add fastness → speed up
加 means add/increase; 快 means fast/quick. Together they literally read as add-speed, hence accelerate or speed up. Common in contexts like 加快速度 (increase the pace).
加 — force 力 + mouth 口
加 is traditionally analyzed as a compound of 力 (strength) and 口 (mouth), suggesting boasting or exaggerating one's effort with words. From this it extended to the meaning 'to add' or 'increase'. Today it is used broadly for addition, both literal and figurative.
快 — heart radical 忄 + 夬 (phonetic)
快 is a semantic-phonetic compound. The heart radical 忄 carries the meaning, since the original sense referred to a feeling of pleasure or delight. The right side 夬 supplies the sound. The meaning later extended from 'pleased' to 'quick, fast', the dominant modern sense.