At the ArtSpring store in Silver Spring,Maryland, visitors can buy products made by local artists and artisans.

VOA: special.2011.03.09

By Spring Break he'd gotten sufficiently sick that his doctor basically said, "You can't continue in school anymore.

春假的时候，他病得十分严重,他的医生直截了当地说，“你不能再上学了。

耶鲁公开课 - 死亡课程节选

We know now with the same spring, by this comparison, we will find all objects now can be attributed a mass.

我们现在知道利用相同的弹簧,采用这种比较的方法,就会发现,所有物体都有确定的质量

耶鲁公开课 - 基础物理课程节选

By the spring of nineteen forty-one, Europe had been at war for a year and a half.

VOA: special.2009.05.17

These risks spring from the fact that philosophy teaches us and unsettles us by confronting us with what we already know.

这风险源自于以下事实,即哲学就是让我们面对自己熟知的事物,然后引导并动摇我们原有的认知。

耶鲁公开课 - 公正课程节选

It is a feeling of restlessness or excitement brought on by the coming of spring.

VOA: special.2010.03.15

And by means I don't entirely understand, Uriah Parmelee, in the spring of 1861, was an Abolitionist.

我不是很明白,乌利亚·帕米利在1861年的春天,还是个废奴主义者

耶鲁公开课 - 美国内战与重建课程节选

A lot of people call South by Southwest Interactive the geek spring break.

VOA: special.2011.03.14

Even in the case of this spring, when you pull it, if you pull it to the right by some force.

甚至是在这样的弹簧问题中,当你拉它的时候,如果你用力向右拉

耶鲁公开课 - 基础物理课程节选

This song by K.D.Lang is about dreaming of spring in cold dark places.

VOA: special.2010.03.15

I draw a graph here of the amount by which I pull the spring versus the force it exerts.

我在这里画个图,纵轴是弹簧的拉伸量,横轴是力的大小

耶鲁公开课 - 基础物理课程节选

And it's from low-flying airplanes each spring that pilots sow the rice crop by tossing seeds from 900-kilo bags into the wind.

VOA: standard.2010.06.17

Newton is not going to come and tell you what force the spring will exert when it's pulled by some amount.

牛顿不会过来告诉你,弹簧被拉伸一定量时会产生多大的力

耶鲁公开课 - 基础物理课程节选

You hook one end of the spring to a wall and you pull it from rest by some amount and you attach the one kilogram mass to it.

你把弹簧的一端固定在墙上,然后拉伸一段距离,接着你把 1 千克物体固定在上面

耶鲁公开课 - 基础物理课程节选

This is the force exerted by the spring on the mass.

这是弹簧对物体的作用力

耶鲁公开课 - 基础物理课程节选

Then, I bring the elephant and I pull the spring by the same amount and I find the acceleration of the elephant and the denominator is obviously the mass of the elephant.

然后我再找来大象,用相同的力去拉弹簧,大象就具有了加速度,很明显,分母就是大象的质量

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

耶鲁公开课 - 基础物理课程节选

The force may taper off, the force may not be given by a straight line, but for modest deformations, every spring will have a linear regime in which the force is linearly proportional to the stretching.

它产生的力可能会渐渐消失,力的曲线可能不是一条直线,而有轻微的弯曲,每个弹簧都有一个线性区间,在这一区间内,力和伸长量是线性关系

耶鲁公开课 - 基础物理课程节选

But if I'm accelerating, the force exerted by the spring and therefore, the needle the weighing machine reads is m.

但是如果我在加速运动,那么弹簧的弹力,也就是称重机上指针的读数就是 m

耶鲁公开课 - 基础物理课程节选

Therefore, it'll compress by an unknown x, which is equal to mg divided by the force constant of the spring.

因此它的压缩量为 x,也就等于 mg 除以弹簧的弹性系数

耶鲁公开课 - 基础物理课程节选

So the spring is being pushed by mg here and mg here.

所以弹簧受到一个向下的 mg 还有一个向上的 mg

耶鲁公开课 - 基础物理课程节选

We did the comparison with the elephant or something; a is the second derivative of x and for this problem, when F is due to a spring, we know the force is that by studying the spring.

我们也已经把它与大象或其它东西作过比较,a 是 x 的二阶导数,在这个问题中,F 是由弹簧产生的,我们在讨论弹簧问题时已经知道了力的大小

耶鲁公开课 - 基础物理课程节选

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

耶鲁公开课 - 基础物理课程节选