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An open system, as the name describes, allows mass and energy to freely flow through the boundary.
开系，顾名思义，允许质量和能量自由地,流过它的边界。
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If a photon which has no mass can behave as a particle, does it follow then an electron which has mass can behave as a wave? 1920.
如果一个没有质量的光子,能像粒子一样运动，那么它能像一个,没有质量的电子那样以波的形式运动吗。
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So, it's a trivial matter, by looking at what is the weight and how far does it drop, to say OK, how much work is done by the paddle wheel.
好，让我们看看重物的质量,以及它下落的距离，就知道桨轮做了多少功。
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One is inertial mass, which is how much you hate your velocity to change, how hard you resist acceleration.
一个是惯性质量,它反映了物体速度改变的难易程度,即保持加速度的难易程度
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And this spin is an intrinsic quality of the electron, it's a property that is intrinsic in all particles, just like we would say mass is intrinsic or charge is intrinsic.
自旋是电子的本征量，它是所有粒子的本征性质，就像我们说质量是本征的或者电荷是本征的。
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It has an atomic mass of two deuterium.
它的质量是等于重氢的质量。
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And I have purposely made the arrow shorter to indicate that it has been slowed because we are going to argue its mass didn't change, so the only way to change its energy is to change its velocity.
我已经故意将这个箭头弄短,用来象征它变慢了,因为我们将证明它的质量没有变，只有它的能量改变了,也就是它的速度变了。
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The closed system allows energy to transfer through the boundary but not mass.
闭系允许能量通过它的边界传递,但质量不行。
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You adjust the lengths and when it balances, you can sort of tell what this mass is, right?
调整它与支点的距离,然后当它平衡时,你就能得到质量是多少,对吧
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We can make some substitutions here using some of the derivation on the previous board which will give us the Planck constant divided by 2 pi mass of the electron times the Bohr radius.
在这里我们也可以,用我以前在黑板上写过的一些词来取代它,得到的是普朗克常数除以2π电子质量,再乘以波尔半径。
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What de Broglie is saying we can know the wavelength of any matter at all, as long as we know its mass and it's velocity.
通过德布罗意所说的,只要我们知道了,它的质量和速度，我们可以知道,任何物质的波长。
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We figured out the mass is so tiny that it shouldn't really deflect them very much.
电子的质量这么小,对它基本不会产生影响。
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0 And it has a mass of 9.11 times 10 to the minus 31 kilograms The charge compensation comes out of the nucleus with the proton and it is positive 1.6 times 10 to the minus 19 coulombs.
它的质量是9。11乘以0,到负31千克,电荷补偿来自于,有质子的原子核,它是+1。6*10^库伦。
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system is the opposite of the open system, no mass and no energy can flow through the boundary.
孤立系与开系正相反，没有质量或能量,能流过它的边界。
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Now I can measure that, because I pull it by one centimeter and I find the acceleration it exerts on a known mass.
现在就能测量这个力了,因为把弹簧拉伸 1 厘米,我就知道它让一个质量已知的物体产生的加速度
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And I will go even further and will predict what its atomic mass is.
我会在深入,还会预测它的原子质量是多少。
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Other is gravitational mass, which is the measure of how much you're attracted to the Earth.
另一个是引力质量,它可以用来衡量地球对物体引力的大小
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12 That gives it a mass number of 312.
所以它的质量数为。
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But its mass is 1800 times that of the electron.
但是它的质量是电子的1800倍。
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And since we are not expecting the mass of the particle to change, what we really are saying is the uncertainty in its velocity times the uncertainty in its position is greater than the ratio of the Planck constant divided by 2 pi.
因为我们不期望,粒子质量发生变化，我们说的是,它速度的不确定度,乘以它位置的不确定度,比普朗克常量,除以2除以圆周率要大。
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8 He predicted 68 for the atomic mass.
他预测它的原子质量是。
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We divide that by the mass, so 0.12 kilograms, that's the mass of a regulation baseball for the major leagues, and the velocity of the baseball is 42 meters per second. So, we can cross out our units doing our unit analysis.
我们用质量来除它，质量为0，12千克，这是大多数联赛规定的棒球质量,棒球的速度为42米每秒,所以，我们可以消去单位,来做单位分析。
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It is the mass of the electron.
它指电子的质量。
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How do you find this mass?
你怎么去测出它的质量
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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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This spring is getting squashed on either side, and it'll squash by certain amount x, that depends on your mass, and that x will be turned into a motion of a needle and that'll read your mass.
这个弹簧两边都会受到压缩,压缩量为 x,它由你的质量决定,x 会转换成指针的运动,你从而可以读数
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