He just said whenever there's an acceleration, it's going to be due to some forces and it's your job to find what the forces are.

他只说过只要有加速度,就说明有力的作用,你们的任务是要找出这些力

耶鲁公开课 - 基础物理课程节选

It's all about market forces and the health and the condition of your product.

所有这一切都取决于市场的需求,以及你的产品的状况和健康情况

耶鲁公开课 - 美国内战与重建课程节选

Do not forget the existing forces and do not make up your own forces.

不要忘记已存在的力,不要自己乱加力

耶鲁公开课 - 基础物理课程节选

Your problem is to only look at the forces of contact on you, and that is just this f.

你只需要注意那些直接作用在这个物体上的力,那就只有 f 了

耶鲁公开课 - 基础物理课程节选

But then you can trace it to some external forces, which are carrying your iPod.

过一会儿你就能发现一些外力的作用,也就是有人把你的 iPod 拿走了

耶鲁公开课 - 基础物理课程节选