mean free path

简明释义

平均自由行程

英英释义

例句

1.When designing vacuum systems, engineers must consider the mean free path of the molecules involved.

在设计真空系统时，工程师必须考虑涉及分子的平均自由程。

2.The mean free path of air molecules is typically around 68 nanometers at standard temperature and pressure.

在标准温度和压力下，空气分子的平均自由程通常约为68纳米。

3.The average distance a molecule travels before colliding with another is known as its mean free path.

一个分子在与另一个分子碰撞之前所能行进的平均距离称为它的平均自由程。

4.In gases, the mean free path can be affected by temperature and pressure.

在气体中，平均自由程会受到温度和压力的影响。

5.Understanding the mean free path is crucial for predicting how gases behave under different conditions.

理解平均自由程对于预测气体在不同条件下的行为至关重要。

作文

The concept of mean free path is fundamental in the field of physics, particularly in the study of gases and particle dynamics. It refers to the average distance a particle travels between collisions with other particles. Understanding this concept is crucial for various applications, including the behavior of gases, the design of reactors in chemical engineering, and even in astrophysics when considering the movement of celestial bodies in a medium. To grasp the significance of mean free path, one must first consider the nature of gas molecules. In a gas, molecules are in constant motion, colliding with each other and with the walls of their container. These collisions can be elastic, meaning that the total kinetic energy is conserved, or inelastic, where energy is transformed into other forms. The mean free path provides a statistical measure of how far a molecule travels before it experiences such a collision. Mathematically, the mean free path (λ) can be expressed using the formula: λ = kT / (sqrt(2) σP), where k is the Boltzmann constant, T is the temperature, σ is the effective cross-sectional area for collision, and P is the pressure of the gas. This equation illustrates how various factors influence the mean free path. For instance, at higher temperatures, the kinetic energy of the molecules increases, leading to a longer mean free path as they travel faster and collide less frequently. Conversely, increasing the pressure results in more frequent collisions, thereby decreasing the mean free path. In practical terms, the mean free path has significant implications in fields such as aerodynamics and material science. For example, in aerodynamics, understanding the mean free path of air molecules is essential for predicting how aircraft will perform at different altitudes. At high altitudes, the mean free path increases due to lower pressure, which affects the flow of air over the wings and can lead to different aerodynamic properties. In the realm of material science, the mean free path plays a role in understanding how particles interact within solids and liquids. For instance, in semiconductors, the mobility of charge carriers is influenced by their mean free path within the material, which affects the efficiency of electronic devices. Furthermore, the concept of mean free path extends beyond traditional physics. In cosmology, researchers consider the mean free path of photons traveling through the universe, which helps them understand the distribution of light and matter in space. The study of cosmic background radiation also involves calculations related to the mean free path of photons as they travel through the expanding universe. In conclusion, the mean free path is a vital concept that bridges various domains of science and technology. Its implications stretch from the microscopic interactions of gas molecules to the macroscopic behaviors observed in engineering and astrophysics. By understanding the mean free path, scientists and engineers can better predict and manipulate the behavior of particles, leading to advancements in technology and a deeper understanding of the natural world.

“平均自由程”这一概念在物理学领域中是基础性的，特别是在气体和粒子动力学的研究中。它指的是粒子在与其他粒子碰撞之间平均行进的距离。理解这一概念对于各种应用至关重要，包括气体的行为、化学工程中反应器的设计，甚至在天体物理学中考虑天体在介质中的运动。要掌握“平均自由程”的重要性，首先必须考虑气体分子的性质。在气体中，分子处于不断运动中，相互碰撞以及与容器壁碰撞。这些碰撞可以是弹性的，意味着总动能被保持，或者是非弹性的，其中能量转化为其他形式。“平均自由程”提供了一个统计度量，表明分子在经历这样的碰撞之前可以行驶多远。在数学上，“平均自由程”（λ）可以用公式表示：λ = kT / (sqrt(2) σP)，其中k是玻尔兹曼常数，T是温度，σ是碰撞的有效截面积，P是气体的压力。这个方程展示了各种因素如何影响“平均自由程”。例如，在高温下，分子的动能增加，导致“平均自由程”变长，因为它们移动得更快，碰撞的频率降低。相反，增加压力会导致更多的碰撞，从而减少“平均自由程”。在实际应用中，“平均自由程”在气动学和材料科学等领域具有重要意义。例如，在气动学中，理解空气分子的“平均自由程”对于预测飞机在不同高度的表现至关重要。在高海拔地区，由于压力较低，“平均自由程”增加，这会影响空气在机翼上的流动，并可能导致不同的气动特性。在材料科学领域，“平均自由程”在理解固体和液体内粒子相互作用方面发挥着作用。例如，在半导体中，载流子的迁移率受到它们在材料内的“平均自由程”的影响，这影响电子设备的效率。此外，“平均自由程”的概念超越了传统物理学。在宇宙学中，研究人员考虑光子在宇宙中传播的“平均自由程”，这有助于他们理解光和物质在空间中的分布。宇宙背景辐射的研究也涉及与光子在扩展宇宙中传播相关的“平均自由程”的计算。总之，“平均自由程”是一个重要的概念，它连接了科学和技术的各个领域。它的影响从气体分子的微观相互作用延伸到工程和天体物理学中观察到的宏观行为。通过理解“平均自由程”，科学家和工程师能够更好地预测和操控粒子的行为，从而推动技术进步并加深对自然世界的理解。