作さ用よう線せん

noun

line of action

Physics term: the line along which a force vector acts.

• 力ちからの作さ用よう線せんが重じゅう心しんを通とおるとき、物ぶっ体たいは回かい転てんしない。

  When the line of action of the force passes through the center of gravity, the object does not rotate.