The ground is a box that is static, which Box2D knows, because the box has zero mass (by default) and therefore doesn't collide with other objects.
地面是一个静止的立方体，这是Box2D已知的，因为这个立方体的质量为零(默认)，因此不会与其他物体相撞。
But astronauts start losing muscle mass within days of entering a zero-gravity environment, and the longer they stay in space, the more their muscles shrink.
航天员在进入零重力环境的几天之内就开始出现肌肉流失。
Only a handful of homes are zero-carbon, however, and many designs are too expensive to merit mass production
然而只有少数家庭是零排放，许多设计太过昂贵，不值得大量生产。
For zero nukes would make no sense if this left the world safe for the sorts of mass conventional warfare that consumed the first half of the 20th century.
如果说零核武意味着是使世界对于充斥20世纪上半页那样的传统大规模战事更加安全，那么它是毫无意义的。
Make v2 zero, and you see exactly that you see here the same result, so this must be the velocity of the center of mass.
使v2为，你显然知道,在这里有同样的结果，它必然是重心速度。
Such current disturbs the zero out-put basic line of the light mass number region, so that it's very difficult to measure and record the height of spectrum peaks of the light mass number region.
这种电子流对轻质量部分质谱的零输出基线起干扰作用，致使这部分谱峰的峰高不能很好地测量和记录。
The object particle means to the microcosmic particle that its static mass is not zero, for example, electron atom molecule and so on.
实物粒子是指静止质量不为零的微观粒子，如电子、原子和分子等。
Two signals from the mass flowmeter are filtered by no change of phase, and the phase difference is given by zero passage arithmetic.
两路信号数据采集后使用了无相位变化的滤波方法，通过过零点算法计算出得出相位差。
These silent, zero-emission gadgets have long been used in NASA spacecraft. They represent the great hope of many environmentalists to power the first mass-produced electric car.
这种低噪声、无排放物的小玩艺儿早就在美国航空航天局的航天器上派上了用场。很多环保主义者对它寄予厚望，期待它能为首批大量生产的电动小轿车提供动力。
From the wave-particle properties of photon, the author presents a method with which the static mass of photon can be deduced to zero.
给出了由光子的波粒二象性推导光子静止质量为零的一种方法。
A hypothetical particle postulated to be the quantum of gravitational interaction and presumed to have an indefinitely long lifetime, zero electric charge, and zero rest mass.
引力微子一种假想粒子，被假定为引力相互作用的量子，并被推测为具有。
A hypothetical particle postulated to be the quantum of gravitational interaction and presumed to have an indefinitely long lifetime, zero electric charge, and zero rest mass.
引力微子一种假想粒子，被假定为引力相互作用的量子，并被推测为具有。
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