加速
かそく · kasoku · JLPT N2 · noun
acceleration
🚀 加速 = 加 (add, increase) + 速 (speed): adding speed = acceleration
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.