The acceleration of a body equals the force exerted on it divided by its mass.物体所受外力除以其质量等于加速度。They believe in outside forces such as luck, fate and chance.他们相信运气、命运与机会之类的外力因素。The play portrays a good marriage torn apart by external forces.这出戏讲述了一段美满的婚姻彻底毁于外力的故事。