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  • General

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  • 建模

    A road map showing routes and geographical features of a region.

    Did you ever read a road map like this one? Maybe not, but you’ve probably made a sketch of a house or other object and played with toy cars or dolls. What do all these activities have in common? They all involve models.
    ::你读过像这样的路线图吗?也许没有,但你可能已经绘制了房屋或其他物体的草图,并且玩玩具汽车或娃娃。 所有这些活动有什么共同之处?它们都涉及模型。

    What Is a Model?
    ::什么是模型?

    A model is a representation of an object, system, or process. For example, a road map is a representation of an actual system of roads on the ground. Models are very useful in science . They provide a way to investigate things that are too small, large, complex, or distant to investigate directly. To be useful, a model must closely represent the real thing in important ways, but it must be simpler and easier to understand than the real thing.
    ::模型代表物体、系统或过程。例如,路线图代表了地面上的实际道路系统。模型在科学方面非常有用。模型提供了一种方法来调查那些太小、大、复杂或远而无法直接调查的东西。为了有用,模型必须以重要的方式密切代表真实的东西,但必须比真实的东西简单易懂。

    Q: What might be examples of things that would be modeled in physical science because they are difficult to investigate directly?
    ::问题:什么是物理科学中因难以直接调查而成为样板的事物的例子?

    A: Examples include extremely small things such as atoms, very distant objects such as stars, and complex systems such as the that carries electricity throughout the country.
    ::A:例子包括原子等极小的东西,恒星等非常遥远的物体,以及全国电力输送系统等复杂系统。

    Q: What are ways that these things might be modeled?
    ::问题:这些事物可以以什么方式模拟?

    A: Types of models include two-dimensional diagrams, three-dimensional structures, mathematical formulas, and computer simulations. Examples of simple two-dimensional models in physical science are described below. 
    ::A:模型类型包括二维图、三维结构、数学公式和计算机模拟。

     

     

     

     

    Simple Models in Physical Science
    ::物理科学简单模型

    The diagram below is a simple two-dimensional model of a water molecule . This is the smallest particle of water that still has the properties of water. The model shows that each molecule of water consists of one of oxygen and two atoms of hydrogen.
    ::下面的图表是水分子的简单二维模型。 这是最小的水粒子, 仍然具有水的特性。 该模型显示, 每个水分子由氧和两个氢原子组成。

    A model of a water molecule showing oxygen and hydrogen atoms, with protons, neutrons, and electrons.

    Q: What else can you learn about water molecules from this model?
    ::问:你还能从这个模型学到什么水分子?

    A: The model shows the number of atomic particles— , , and electrons—in each type of atom. It also shows that each hydrogen atom in a water molecule shares its with the oxygen atom.
    ::A:模型显示了原子在每种原子中的原子粒子-和电子数量,还表明水分子中的每个氢原子都与氧原子分享。

    Q: Do you think this water molecule model satisfies the criteria of a useful model? In other words, does it represent a real water molecule in important ways while being simpler and easier to understand than a real water molecule?
    ::问题:你认为这个水分子模型符合一个有用模型的标准吗? 换句话说,它是否在重要方面代表一个真正的水分子,同时比一个真正的水分子简单易懂?

    A: The model shows the basic structure of a water molecule and how the atoms in the molecule share electrons. These features of the water molecule explain important properties of water. The model is also simpler and easier to understand than a real water molecule. In a real molecule, electrons spin around the nuclei at the center of the atoms in a cloud, rather than in neat, circular orbits, as shown in the model. The atoms of a real water molecule also contain even smaller particles than protons, neutrons, and electrons. For many purposes, however, it’s not necessary to represent these more complex features of a real water molecule.
    ::A:模型显示了水分子的基本结构,以及分子中的原子如何分享电子。水分子的这些特征解释了水的重要特性。模型比真正的水分子更简单、更容易理解。在真正的分子中,电子在原子的中心绕着核旋转,在云层中,而不是在圆形轨道中。如模型所示,真正的水分子原子也包含比质子、中子和电子更小的粒子。然而,在许多方面,不需要代表真正的水分子的这些更复杂的特征。

    The diagram below shows another example of a simple model in physical science. This diagram is a model of an electric circuit . It represents the main parts of the circuit with simple symbols. Horizontal lines with + and – signs represent a battery. The parts labeled R 1 , R 2 , and R 3 are devices that use electricity provided by the battery. For example, these parts might be a series of three light bulbs.
    ::下面的图表显示了物理科学中一个简单模型的另一个例子。 这个图表是电路的模型。 它代表电路的主要部分, 带有简单的符号。 水平线加上+ - 符号代表电池。 标有R1、 R2 和 R3 的部件是使用电池提供的电力的设备。 例如, 这些部件可能是三个灯泡的系列。

    Model of an electric circuit showing battery and devices using simple symbols.

    Q: In the electric circuit diagram, what do the black lines connecting the battery and electric devices represent?
    ::问题:在电路图中,连接电池和电力装置的黑线代表什么?

    A: The black lines represent electric wires. The wires are necessary to carry electric current from the battery to the electric devices and back to the battery again.
    ::A: 黑线代表电线;电线是将电流从电池输送到电动装置,再回回电池所必需的。

    Q: How is a circuit diagram simpler and easier to understand than an actual electric circuit?
    ::问题:电路图如何比实际电路简单易懂?

    A: A circuit diagram shows only the parts of the circuit that carry electric current, and it uses simple symbols to represent them.
    ::A:电路图只显示电流的电路部分,使用简单的符号表示。

    Summary
    ::摘要

    • A model is a representation of an object, system, or process that is simpler and easier to understand than the real thing.
      ::模型代表物体、系统或过程,比真实事物简单易懂。
    • Examples of simple models in physical science include two-dimensional models of molecules and electric circuits.
      ::物理科学简单模型的例子包括分子和电路的二维模型。

    Review
    ::回顾

    1. What is a model?
      ::什么是模型?
    2. Why are models useful in science?
      ::为什么模型在科学方面有用?
    3. Identify characteristics of a good model.
      ::确定良好模式的特点。
    4. Describe a simple model in physical science.
      ::描述一个简单的物理科学模型。