音速的

Hypersonic aircraft refers to the speed of sound, at least 5 times more than the aircraft.

高超音速飞机是指超过音速至少5倍的飞机。

If a plane is flying at Mach 2, it is flying at twice the speed of sound.

假如飞机以二马赫的速度飞行，那么它的速度就是音速的两倍。

It announced a programme "to establish the technology foundation by 2001 to support the US transport industry's decision for a 2006 production of an environmentally acceptable, economically viable aircraft with notional design features of 300 seats, 5,000 nautical mile range and a M2.4 cruise speed."

NASA还公布了"要在2001年前为支持美国运输工业的目标奠定科技基础。这个目标就是能在2006年建造一种环境舒适，价格合理的，在预想的设计中具有300个座位，5000英里航程并且巡航速度达到2.4倍音速的飞机。"

The subsonic region is the exterior of the hole: Sound waves can propagate upstream but only at the expense of being stretched, like light being redshifted.

次音速的区域则对应到黑洞之外的时空：声波能够往上游传播，而唯一的代价是波长被拉长，就像光会被红移一样。

In airplane design, structural nonlinearities cannot be avoided. The structuralnonlinearities arise from worn hinges of control surfaces, loose control linkages,material behavior and various other sources. In the flighting, the aerodynamicnonlinearities also cannot be avoided. The aerodynamic nonlinearities can benegligible when the speed of the plan is not very high;but when the speed of the planis supersonic or highly supersonic, it cannot be negligible.

在飞机设计中，结构非线性是不可避免的，结构非线性源于控制其表面的旧铰链，松散的控制器联动装置，材料性能和其它的来源；在飞机的飞行中，气动的非线性也是不可避免的，对于飞行速度不是很高的情况，气动的非线性是可以忽略的，而对于超音速以及超高音速的飞机来说，气动的非线性是不可以忽略的。

The free water in wood is very closely related to the density change of wood during drying, so that the sound speed measured by tap tone completely obeys the physical law relating sound speed and properties of solid materials. 2. When moisture contents are higher than the fiber saturation point, the weight changes or the moisture content changes of the wood can be estimated with high accuracy by measuring the changes of sound speed using the tap tone method.

试验结果显示：木材中之自由水分在打音时完全表现在生材之密度变化上，因此打音音速完全遵守音速与材质关系之基本物理定律，故在含水率高於纤维饱和点之生材状态，利用音速变化来推定木材重量变化或含水率变化具有相当高的精度，是合理可行的。

What's more, as the vehicle approaches the speed of sound, it produces a frontal shock wave which liquefies the earth ahead, so the wheels end up carving through ground, rather than simply rolling over it.

更重要的是，由于车辆接近音速的，它产生正面冲击波的液化地球未来，所以车轮最终通过地面雕刻，而不是简单地在它滚动。

CNN -- Fifty-seven years after combat pilot Chuck Yeager broke the sound barrier, NASA will make a second attempt Saturday at flying an aircraft at 5,000 mph -- about seven times Mach 1, the speed of sound.

现在，NASA(美国国家航空和宇宙航行局)将于周六进行时速5000英里的喷气式飞机的第二次试飞，这个速度大约为音速的7倍----7马赫。

CNN -- Fifty-seven years after combat pilot Chuck Yeager broke the sound barrier, NASA will make a second attempt Saturday at flying an aircraft at 5,000 mph -- about seven times Mach 1, the speed of sound.

57年前，战斗机飞行员Chuck Yeager首次突破了音障。现在，NASA(美国国家航空和宇宙航行局)将于周六进行时速5000英里的喷气式飞机的第二次试飞，这个速度大约为音速的7倍----7马赫。

Mach'.'' 2, it is flying at twice the speed of sound.

假如飞机以二马赫的速度飞行，那么它的速度就是音速的两倍。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。