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Now, gravity, well force, is equal to mass times acceleration, g and the acceleration due to gravity is g.
是重力，等于质量乘以加速度，由重力导致的加速度是。
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And the idea was that gravity did work on the water and falling, and that work led to the generation of heat.
焦耳的想法是,重力对水，做了功。
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When the charge is applied, if the upper plate is negative, we would expect that the negative droplet would be repelled at a rate exceeding the gravitational fall.
当电荷起作用时，如果上边的板子是负电的，我们可以期待负电的液滴会,超过重力下降速度的速度被排斥。
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But gravity has a remarkable property that the pull of the Earth is itself proportional to the inertia of the object.
重力有一个显著特征,即地球的引力,与物体的质量成比例
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They seem to be going somewhere and there's this sort of force of pull or gravity in music having to do with some chords wanting to go to other chords.
和弦向某一个方向发展，就像有一股力量拉着它们,或者说音乐的重力吸引着它们，让一些和弦想行进成为另一些和弦。
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One should do," he says, "what archers do when attempting to reach a distant target, namely, aim your bow high, knowing that the force of gravity " will bring the arrow down."
他说：，“一个人应该做的是，模仿伟人所为,当试图达致遥不可及的目标时，意即将目标设高，明了重力会将,射出的箭吸回地面“
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That is, you minimize potential energy and you see things falling under the force of gravity and so forthgoing to potential energy minima in conformance with this result.
换句话说，你使得势能最小化,然后发现我们关注的东西,在重力或者其他力的作用下下落,直到势能最小的地方,这和我们刚才的结果是一致的。
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You might be winded doing it the second way, but when you get to the top and you are at the 60th story your gravitational potential is independent of how you got there.
对于走路你可能很抓狂，但你一旦到了顶层,你就是在第60层,你的重力势能,与你如何到达那里无关。
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You know, if you want to measure the potential energy of something in a gravitational field, you have to define the zero somewhere, right, because it's arbitrary. You can set it anywhere you want. It's the same with enthalpy.
你知道，如果你想测量重力场,中某种东西的势能，你需要，在某处定义一个零点，对吧？,因为势能的值是任意的,你可以把它设定在。
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By the way, when I say there's 10 Newtons acting this way, you might say, "What about gravity? What about the table?"
顺便提一下我说有 10 牛的作用力,你也许会问,"那重力呢,桌子对它的力呢"
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Whether you take the elevator to the top of the Hancock Tower or whether you walk up the stairs, the change in gravitational potential is identical.
不管你是乘电梯,去大厦的顶层,或者是步行，重力势能的变化是相同的。
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We all know that in a falling elevator, you definitely do not escape the pull of gravity.
我们都知道在一个下坠的电梯里,你当然还是会受到重力的
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And we know about gravity, and we know about work.
我们都了解重力，也都了解功。
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If you escape the pull of gravity, your spaceship will be off, won't be orbiting the Earth.
如果你完全脱离重力,太空船早就飞得没影了,而不是在轨道上运行
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If there is no charge on the plate, these droplets will simply fall under gravity.
如果在板子上没有电荷，这些液滴就只会由于重力掉下。
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This also tells you that the mass of an object has nothing to do with gravitation.
这也表明,物体的质量与重力无关
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Imagine that this is in outer space where there is no gravity for now.
就假设现在这是在没有重力的外太空
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The reason it comes down is gravity is pulling it.
物体向下运动是因为重力作用
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If all you know is the particle is falling under the affect of gravity, that's not enough to say where the particle is, right?
如果你只知道,质点受重力作用下落,那并不足以表明物体的位移,对吧
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So, you will feel weightless for a short time or you'll feel your weight is little.
所以你会短时间的感觉到无重力,或者感到自己变轻了
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It's wrong to think that you feel weightless because you escaped the pull of gravity.
但是要是你认为失重,就是不受重力那就大错特错了
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For example, let's take the case where the particle is falling under gravity.
比如说,举个例子,一个质点正在重力的作用下下落
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It is the same thing as gravitational energy.
就像重力势能。
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It doesn't rely on gravity. It doesn't rely on the planet.
这不需要依赖重力,不需要依赖地球
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They have not escaped the pull of gravity either.
他们也不是完全不受重力
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You don't feel any weight because your weight is the opposition you get to falling through the floor; but if the floor is giving way and you're just falling freely, you feel weightless.
你不会感到重力,是因为你的重力在阻碍你穿过地板,如果没有地板,你自由下落,也感觉不到重力
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You feel heavy and it reads more because the poor spring not only has to support you from falling through the floor, but also accelerate you counter to what gravity wants to do.
你感到自己变重以及读数增加,因为现在弹簧不仅要支撑你,不让你掉下来,还要抵消重力的作用让你加速
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It knows that this particle happened to have a height of 15, at the time of 0, and a velocity of 10, and it is falling under gravity with an acceleration of -10.
这个质点恰好处在高度为15的地方,零时刻,初速为10,并在重力作用下以-10的加速度下坠
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They have just stopped fighting it.
只是不用抵抗重力了
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Later on, we know about gravity.
我们以后会讲到重力
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