動力
どうりょく · douryoku · JLPT N1 · noun
power
⚡ 動 (move) + 力 (force) = the force that makes things move; power as motive force
動 means move or act and 力 means force or strength, so 動力 is the force that sets something moving. Think of it as the engine's push that drives a machine forward.
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'.