Gravity is one force that acts on a body without the source of the force actually touching it.

引力是一种受力物体收到了力的作用,但却没有接触施力物体的力

耶鲁公开课 - 基础物理课程节选

And so, you know from your Newtonian mechanics, as you were learning in 8.01, the dynamic force here mv^2/r is mv squared over r.

在8。01节对牛顿动力学系统的学习中，我们可以知道这里的运动受力,就是。

麻省理工公开课 - 固态化学导论课程节选

Okay, so with that, if you write the right forces, you will be just fine.

本着这个原则如果你受力分析画对了,那就功德圆满了

耶鲁公开课 - 基础物理课程节选

But there's another way to do this and I'm going to give you now the simplest example of the other way, which is to draw free-body diagrams.

不过还有另外一种方法,现在我来给你们演示,另外一种方法最简单的例子,也就是隔离法的受力分析

耶鲁公开课 - 基础物理课程节选

Maybe you should complete the force acting on this one.

也许该由你们来完成它的受力分析

耶鲁公开课 - 基础物理课程节选

I am going to say if that electron is to stay in its orbit, that is to say it doesn't flee the atom, it doesn't collapse under the nucleus then the sum of the forces on the electron must be zero No net force. And so that will be the sum of a dynamic force plus an electrostatic.

如果电子会保持在它的轨道上运行,既不脱离原子的话，它就不会由于原子核对它的吸引力而被瓦解掉,电子所受的合力一定为零,由于没有合力,所以电子所受力为动态力和静电力的总和。

麻省理工公开课 - 固态化学导论课程节选