14.1 能源
章节大纲
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These young children are very active. They seem to be brimming with energy. You probably know that lots of things have energy—from batteries to the sun. But do you know what energy is? Read on to find out.
::这些孩子非常活跃。他们似乎充满了能量。你也许知道,从电池到太阳,很多东西都有能量。但你知道什么是能量吗?你看看吧。Defining Energy
::界定能源Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work, which means using force to move an object over a . When work is done, energy is transferred from one object to another. For example, when the boy in the Figure uses force to swing the racket, he transfers some of his energy to the racket.
::在科学中,能源被定义为以某种方式移动物质或改变物质的能力。能源也可以被定义为工作的能力,这意味着用武力将物体移动到一个物体之上。当工作完成时,能量从一个物体转移到另一个物体。例如,图中的男孩用武力挥动电动,他将部分能量转移到电动。Q: It takes energy to play tennis. Where does this boy get his energy?
::问:打网球需要能量。这个男孩从哪里得到能量?A: He gets energy from the food he eats.
::A:他从食物中获取能量。SI Unit for Energy
::SI 能源股Because energy is the ability to do work, it is expressed in the same unit that is used for work. The SI unit for both work and energy is the joule (J), or newton ∙ meter (N ∙ m). One joule is the amount of energy needed to apply a force of 1 newton over a distance of 1 meter. For example, suppose the boy in the Figure applies 20 newtons of force to his tennis racket over a distance of 1 meter. The energy needed to do this work is 20 N ∙ m, or 20 J.
::由于能源是工作能力,因此用同一单位表示,工作与能源的SI单位是焦耳(J)或牛顿表(N / mm)。一个焦耳是指在1米的距离内应用1牛顿的能量量。例如,图中的男孩将20牛顿的力量用在1米的距离内他的网球拍打上。这项工作所需的能量是20牛顿或20焦耳。Energy Has Many Forms
::能源有多种形式If you think about different sources of energy—such as batteries and the sun—you probably realize that energy can take different forms. For example, when the boy swings his tennis racket, the energy of the moving racket is an example of mechanical energy . To move his racket, the boy needs energy stored in food, which is an example of chemical energy . Other include electrical, thermal, light, and sound energy . The different forms of energy can also be classified as , , or a combination of the two. Kinetic energy is the energy of moving matter. Potential energy is energy that is stored in matter.
::如果你想到不同的能源——例如电池和太阳——你可能意识到能源可以采取不同的形式。例如,当男孩摇动网球拍时,移动电拍的能量就是机械能源的一个例子。要移动电拍,男孩需要储存在食物中的能量,这是化学能源的一个例子。其他能源包括电、热、光和声音能源。不同的能源形式也可以被归类为,或者两者的组合。动能是移动物质的能量。潜在的能量是存储在物质中的能量。Q: Is the chemical energy in food kinetic energy or potential energy?
::问题:化学能量是食品动能还是潜在的能量?A: The chemical energy in food is potential energy. It is stored in the that make up food molecules. The stored energy is released when we digest food. Then we can use it for many purposes, such as raising our arms (mechanical energy) or staying warm (thermal energy).
::甲:食物中的化学能量是潜在的能量。它储存在构成食物分子的能量中。当我们消化食物时,储存的能量就会释放出来。然后我们可以将它用于许多目的,比如举起我们的武器(机械能源 ) , 或者保持温暖(热能 ) 。Q: What is an example of kinetic energy?
::问题:什么是动能的例子?A: Anything that is moving has kinetic energy. An example is a moving tennis racket.
::A:移动中的任何事物都有动能。一个例子就是移动中的网球拍。Summary
::摘要-
Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work.
::能源在科学中被定义为以某种其他方式移动物质或改变物质的能力。 能源也可以被定义为工作的能力。 -
The SI unit for energy and work is the joule (J), or newton meter (N ∙ m or Nm).
::用于能源和工作的SI单元为焦耳(J)或牛顿计(N l m或Nm)。 -
Energy exists in different forms, such as mechanical energy and chemical energy. Forms of energy can also be described as kinetic energy, potential energy, or both..
::能源以不同形式存在,如机械能源和化学能源,能源形式也可以被描述为动能、潜在能源或两者兼有。
Review
::回顾-
How is energy defined in science?
::科学如何界定能源? -
What is the SI unit for energy?
::什么是SI单位的能源? -
Name two forms that energy may take.
::列出能量可能采取的两种形式。 -
Which type of energy is the energy of a moving tennis ball? Is it kinetic energy or potential energy?
::移动网球的能量是哪种能源?是动能还是潜在能量?
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Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work.
