Therefore, when you divide by the mass to get the acceleration, the response of different bodies is inverse to the mass.

因此,当你拿力除以质量得到加速度时,不同物体的加速度与质量成反比

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So, a massless body cannot have a net force on it, because the acceleration of the rope cannot be infinite.

所以没有质量的物体不会受到力,因为绳子的加速度不可能是无穷大

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And so we know the force for a particular mass, and we know the area of the piston.

我们知道每个质量对应的力，也知道活塞的面积。

麻省理工公开课 - 热力学与动力学课程节选

But the acceleration it produces on the elephant and on the mass, are in an inverse ratio of their masses.

但这个力使大象和物体产生的加速度,与它们的质量成反比

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So, massless bodies will always have, like a massless rope, equal and opposite forces on the two ends.

所以无质量的物体,比如这个绳子,两边所受的力永远都相等

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Mass of an object is how much it hates to accelerate in response to a force.

物体的质量,反映了物体在力的作用下加速的难易程度

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If you look at the electrical force, the force of electricity, proton and electron or something, it's not proportional to the mass of either object.

如果你考察电作用力,即电现象产生的力,质子啊,电子啊,或者其它什么东西,这种力不和物体的质量成比例

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There's nothing to do here, because the forces are 0, the mass is 0.

就不用管这里了,因为这里的力是 0,质量也是 0

耶鲁公开课 - 基础物理课程节选

You cannot say to me, "Take a force, due to a spring, and see what force it applies and divide by the acceleration and get the mass, " because we haven't defined force, either.

你不能说,"给弹簧施加一个力,看看它能提供多大的力,然后除以加速度,得到质量",因为我们还没给力下一个定义

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First one says, if you knew the force acting on any body, without going into what caused the force, then you may set that force equal the mass times acceleration of the body.

第一部分是,如果你知道作用在任一物体上的力,无论这个力的来源是什么,都可以令力等于质量乘以物体的加速度

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That's how by either balancing the unknown force with a known force or by simply measuring the acceleration as I fall towards this podium and multiplying by mass, you can find the force that exerts on me.

我们既可以让未知力与已知力平衡,也可以只测量我冲向讲台时加速度的大小,再与我的质量相乘,都能求出作用在我身上的力的大小

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In fact, there's a property of gravitational fields anywhere, even in outer space, but there is some residual field between all the planets and all the stars in the universe, that the force on a body is proportional to the mass of the body.

实际上,这是任何地方的引力场都具备的属性,甚至是在外太空,在所有的行星和恒星之间,存在着某种剩余场,在这个场里作用在物体上的力,和物体的质量之间存在比例关系

耶鲁公开课 - 基础物理课程节选