1.3能量的形式和变化
Section outline
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Lesson Objectives
::经验教训目标- Identify different forms of energy.
::查明不同形式的能源。
- Describe how energy changes form.
::描述能源变化的形式。
Lesson Vocabulary
::词汇表课程- chemical energy
::化学化学能
- electrical energy
::电力电能
- electromagnetic energy
::电磁能
- mechanical energy
::机械能源
- sound energy
::健全能源
- thermal energy
::热热能能
Introduction
::导言The man below is playing an electric guitar. He plucks the strings of the guitar with great skill. The sounds of the music thrill the crowd. The bright stage lights add to the excitement. Unfortunately, the lights can also make it uncomfortable for the musician. It can get really warm on stage. Do you know why? It has something to do with the lights. This scene represents energy in many forms. Can you name them all?
::下面的人正在演奏电动吉他。 他以高超的技巧拔出吉他弦。 音乐的声音刺激了人群。 明亮的舞台灯光增加了兴奋。 不幸的是, 灯光也会让音乐家感到不舒服。 它可以在舞台上变得非常暖和。 您知道为什么吗? 它与灯光有关。 这个场景以多种形式代表着能量。 您能给它们命名吗 ?How many different forms of energy can you identify in this picture? Comparing Forms of Energy
::比较能源形式Energy can exist in many forms. It also has the ability to do work. Think about when you do work. You need a lot of energy. Maybe your energy comes from a good breakfast. Your body turns the food you eat into energy. This energy gives you the strength to do work. There are many forms of energy. They all have the ability to do work. From the picture above, can you find six forms of energy?
::能源可以以多种形式存在。 它也可以有工作的能力。 想想什么时候工作。 您需要很多能量。 也许你的能量来自良好的早餐。 也许你的身体可以把食物变成能量。 这种能量能给你做工作的力量。 有很多种能量。 它们都有工作的能力。 从上面看, 你能找到六种能源吗?The guitarist can play because he eats food. Food contains chemical energy. His body then turns chemical energy into motion. His hands can move to play the guitar. The motion of the guitar player's hands is a form of mechanical energy. Chemical energy is just one form of energy. That's why it's important for you to eat right.
::吉他手可以玩,因为他吃食物。 食物含有化学能量。 然后他的身体将化学能量变成运动。 他的手可以动弹吉他。 吉他手的动作是一种机械能量。 化学能量只是一种能量形式。 这就是为什么你必须吃正确的东西。What about some other forms of energy in this picture? How about the stage lights? The stage lights use electrical energy. The lights give off both light and heat. Heat is sometimes called thermal energy. The guitar uses electrical energy. The guitar produces sound energy when the strings are plucked.
::图片中的其他能源形式呢? 舞台灯如何? 舞台灯使用电能。 灯光会熄灭光和热能。 热能有时被称为热能。 吉他使用电能。 当字符串被拔出时吉他能产生声音能量。Mechanical Energy
::机械能源Mechanical energy is a combination of the energy of motion or position. This type of energy describes objects that are moving or could move.
::机械能是运动或位置能量的组合,这种能量是指正在移动或可以移动的物体。A moving ball can have energy from motion. An arrow can also have the energy of motion. Both are types of mechanical energy. Can you think of some other examples?
::移动球可以从运动中获得能量。 箭头也可以从运动中得到能量。 两者都是机械能量。 你能想到其他例子吗 ?Where does the energy of motion come from? It comes from the energy created by position. This energy is stored energy. This means it is not moving yet, but it has the potential to move. How can you store energy?
::运动的能量来自何处? 它来自位置所创造的能量。 这种能量是储存的能量。 这意味着它还没有移动, 但是它有移动的潜力。 您如何储存能量呢 ?In the below, the arrow gains energy from the drawn bow. As the arrow is released, the bow releases its stored energy and puts the arrow into motion. Can you think of some other ways to store energy using position?
::在下面,箭从拉弓中增生能量。当箭被放出时,弓释放了储存的能量,并让箭动起来。你能想到用位置储存能量的其他方法吗?Kinetic and potential energy add up to mechanical energy. Chemical Energy
::化学能源Energy is stored in chemical compounds. This energy is called chemical energy. Chemical energy is a form of potential energy. When bonds between atoms are broken, energy is released. The wood in fireplaces has chemical energy. The energy is released as heat and light when the wood burns.
::能源储存在化学化合物中,这种能源被称为化学能源。化学能源是一种潜在的能源形式。当原子间断裂时,释放出能量。壁炉中的木材具有化学能量。当木材燃烧时,释放出热和光等能量。Most living things get their energy from food. When food molecules are broken down, the energy is released. It may then be used to do work, like playing ball or studying science. If you have ever heard, "Eat a good breakfast," that's why. You need energy to do things during the day. To do those things you need energy. You get your energy from the food you eat. That energy is stored in your body until you need it.
::大多数生物都从食物中获得能量。当食物分子分解后,能量就会释放出来。然后,它可能被用来工作,比如玩球或研究科学。如果你听说过,“吃个好早餐 ” 。这就是为什么你需要能量在白天做一些事情。做那些你需要能量的事情。你从食物中获取能量。能量储存在身体中,直到你需要。How did you get to school today? If you walked, you used chemical energy from the food you ate. What if you rode the bus or were driven in a car? Where did that energy come from? Gasoline also has potential energy. Just like food, when the bonds between atoms in the gas are broken, energy is released. Remember, when wood burns it gives off heat and light. When gasoline is burned in an engine, it also gives off energy. It is this energy that makes the vehicle move.
::今天你是怎么上学的?如果你走路,你用你所吃的食物中的化学能源。如果你乘公交车或乘车,那又如何?这种能源是从哪来的?汽油也有潜在的能量。就像食物一样,当天然气中的原子断裂时,释放能量。当木柴燃烧时,它释放热和光。当汽油在引擎中燃烧时,它也释放能量。正是这种能量使汽车移动。Chemical energy is stored in wood and released when the wood burns. Electrical Energy
::电力能源Electrons are particles in an atom. They have a negative charge. Anything that is moving has energy, even electrons. We often refer to this motion as electricity. Electricity is the result of the moving electrons. These electrons can move through wires. This motion is what makes it possible to watch TV and talk on your cell phone.
::电子是原子中的粒子。 它们有负电荷。 移动中的任何事物都有能量, 甚至电子。 我们经常将这种运动称为电。 电是移动电子的结果。 这些电子可以通过电线移动。 这样的动作使得可以观看电视和在你的手机上交谈。Have you ever had to live without electricity? This can happen after big storms. Any type of natural disaster can cause a loss of electricity. In what ways would a loss of electricity affect your family?
::任何类型的自然灾害都会造成电力损失。 电力损失会以何种方式影响你的家人?Most of the electricity we use comes from power plants. It arrives in our homes through wires. There are also other sources of electricity. You are probably very familiar with two of the most common sources. You can see both of them pictured in the Figure .
::我们使用的大部分电力来自发电厂,通过电线进入我们的家庭。还有其他电力来源。您可能非常熟悉两种最常见的电源。您可以从图中看到这两种电源。A lightning bolt is a powerful discharge of electrical energy. A battery contains stored chemical energy and converts it to electrical energy. Nuclear Energy (Advanced Topic)
::核能(高级专题)The center of an atom is held together by powerful forces. This gives them a huge amount of stored energy. This type of energy is called nuclear energy. This energy can be released and used to do work. This happens in nuclear power plants where they split apart the nucleus of an atom. This splitting apart is called nuclear fission.
::原子的中心是由强大的力量支撑在一起的。 这给了它们大量的储存能源。 这种能源被称为核能。 这种能源可以释放出来,用来工作。 这发生在核电厂, 核电厂将原子的核心分离出来。 这种分裂被称为核裂变。Another type of nuclear energy happens in the Sun. Here the atoms' nuclei are not split apart. Instead, the nuclei of the atoms are fused, or joined together. This process is called nuclear fusion. Some of the sun’s energy travels to Earth. This energy from nuclear fusion warms the planet and provides the energy for photosynthesis (see Figure ).
::另一种核能发生在太阳中。 在这里,原子的核核没有分裂。 相反,原子的核是结合或结合的。 这个过程被称为核聚变。太阳的某些能量流向地球。核聚变的能量使地球变暖,为光合作用提供了能量(见图 ) 。In the sun, hydrogen nuclei fuse to form helium nuclei. This releases a huge amount of energy, some of which reaches Earth. Thermal Energy
::热热能Atoms are in constant motion. They have kinetic energy, the energy of motion. All that motion gives matter thermal energy. The amount of motion that particles have is what we call temperature.
::原子在不断运动。它们有动能, 运动的能量。所有这些运动都提供物质热能。 粒子的运动量就是我们所说的温度。In Figure , you can see two items. They have different amounts of thermal energy, but the same temperature. How can this be?
::在图中,您可以看到两个项目。它们有不同的热能量,但温度相同。这怎么可能?Thermal energy depends on two factors. The first is how fast the atoms are moving, or its temperature. The second is how many atoms the object contains. Therefore, an object with more mass has greater thermal energy. An object with less mass has less thermal energy.
::热能取决于两个因素。第一个因素是原子移动的速度或温度。第二个因素是物体包含多少原子。因此,质量较大的物体具有更大的热能。质量较小的物体的热能较少。Think of it this way. You have a small cup of warm water. You also have a large barrel of warm water. Each are the same temperature. Which has the most energy? If you said the large barrel, you would be correct. The more mass there is, the more thermal energy. If you were in a bath tub and needed to warm the water, would you add a little warm water or a lot? Of course, you would add the larger amount. This is because it has more thermal energy.
::以这种方式来想吧。 您有一小杯温暖的水。 您也有一桶暖水。 每个都是相同的温度。 每个都是相同的温度。 哪个是最大的能量? 如果您说大桶, 你就会说对了。 质量越大, 热能越高。 如果您在浴缸里, 需要取暖水, 你会加一点热水还是很多? 当然, 您会加更多。 这是因为它有较多的热能 。Atoms are moving at the same speed in the soup on the spoon as they are in the soup in the pot. However, there are more atoms of soup in the pot, so it has more thermal energy. Electromagnetic Energy
::电磁能Our sun and other stars release light energy. At least this is what we see. Our Sun and stars also emit more than just light. Scientists call the type of energy that our Sun and stars release electromagnetic energy. This form of energy travels through space. Electromagnetic energy includes the light we see. It also includes much more. Many of these things we know about, but don't always think about. Electromagnetic energy includes radio waves, microwaves, and X rays. We now have devices in our homes and offices that release these same forms of energy. We use electromagnetic energy to make our lives better.
::我们的太阳和其他恒星释放了光能。至少这就是我们所看到的。我们的太阳和恒星也释放的不仅仅是光。科学家们称之为我们的太阳和恒星释放的电磁能量的类型。这种能源形式在空间中穿梭。电磁能源包括我们所看到的光。它还包括更多的光。我们所知道的很多这些事物,但不总是想到。电磁能源包括无线电波、微波和X光。我们现在在我们的家庭和办公室里有装置释放同样的能量形式。我们用电磁能源来改善我们的生活。Radio waves, microwaves, and X rays are examples of electromagnetic energy. Sound Energy
::健全能源The drummer in Figure is hitting the drumheads with drumsticks. This causes the drumheads to vibrate. The vibrations pass to surrounding air particles. Vibrations then pass from one air particle to another in a wave of energy called a sound wave. We hear sound when the sound waves reach our ears. Sound energy can travel through air, water, and other substances. Sound cannot travel through empty space. Sound needs particles of matter to pass it on.
::图中的鼓手正在用鼓棒敲打鼓头。 这会使鼓头振动。 振动会传到周围的空气颗粒上。 振动会在一个叫做声波的能量波中从一个空气粒子传到另一个空气粒子上。 当声音波到达我们的耳朵时, 我们听到声音。 声音能通过空气、水和其他物质传播。 声音无法通过空空空间传播。 声音需要物质粒子来传递它 。You can think of sound moving through matter like falling dominoes. If they are lined up, one will fall, hitting the next and making it fall, and so on. What if the dominoes were too far apart to touch when they fell? This is what happens if there are no particles for sound to travel through. Fortunately for us, space is the only place sound cannot be transmitted.
::你可以想象声音在物质中移动,比如掉下来的多米诺。如果它们被排成一列,一个人会倒下,打下一个,然后倒下来,等等。如果多米诺在坠落时太远,触不到它们,那会怎样?如果没有粒子可以发出声音,那么情况就是这样。幸运的是,对于我们来说,空间是唯一不能发出声音的地方。Vibrating objects such as drumheads produce sound energy. How Energy Changes Form
::能源变化的形式Energy often changes from one form to another. For example, the drummer transfers motion to sound energy. When the moving drumstick strikes the drum head, the drum starts to vibrate. The motion of the vibrating drum head creates the sound you hear. Any form of energy can change into any other form. Frequently, one form of energy changes into two or more different forms. Have you ever sat in front of a campfire? What are two things you notice? The fire creates light. It is also warm by the fire, meaning it creates heat. The energy of the fire comes from the stored energy in the wood. The wood contains chemical energy. As it burns, the chemical energy is changed into light and heat. Not all chemical energy changes produce light and heat. Our cars use gasoline as a fuel. Gasoline contains chemical energy. When our cars burn gasoline in their engines, it is converted into motion and heat.
::能量往往从一种形式变化到另一种形式。 例如,鼓手将运动转向声音能量。 当鼓棒移动到鼓头时, 鼓开始振动。 振动鼓头运动会发出你听到的声音。 任何形式的能量都可以改变为任何其他形式。 一种形式的能量通常会改变为两种或两种以上形式。 你曾经坐在野火前吗? 你注意到的两件事是什么? 火能能创造光亮; 火能也会发亮, 意思是热能。 火能的能量来自木材中储存的能量。 木材含有化学能源。 化学能源随着燃烧, 化学能源会改变为光和热能。 不是所有化学能源都会改变为光和热能。 我们的汽车用汽油作为燃料。 汽油含有化学能源。 当我们的汽车在引擎中燃烧汽油时, 它会变成运动和热力。Energy is constantly changing form. Can you think of other examples of energy conversions? When energy changes forms, energy is conserved. What does this mean? It means that no energy is lost. That does not mean all the energy that changes form goes where we want it. For example, when our cars burn gasoline, all the energy does not go into motion. Some is turned into heat. For us, this energy is wasted. Although you may start with the same amount as you end up with, some of the energy is not useful. In the case of a car engine, some energy may turn into heat energy due to friction. For example, not all of the energy put into a steam turbine in Figure changes to electrical energy. Some changes to thermal energy. This, too, happens because of friction. In this case, it is because of the turning blades and other moving parts. The more efficient a device is, the less thermal energy is lost. Some new appliances are very efficient. These devices have the "Energy Star" label. You can see an Energy Star label in Figure . These labels tells us the appliance is efficient and reduces the use of energy.
::当能源变化的形式, 节能是节能的。 这意味着什么? 这意味着没有能量的丧失。 这并不意味着变化的能量都流向我们想要的地方。 例如, 我们的汽车燃烧汽油, 所有能源不会发生运动。 有些能量会变成热。 有些能量会变成热。 对我们来说, 这种能量是浪费的。 尽管你可以从与你最后一样的量开始, 但有些能量是没有用处的。 对于汽车发动机来说, 有些能量可能会因为摩擦而变成热能。 例如, 并不是所有的能量都会被投入到电动涡轮机中, 电动能的变化图中。 一些热能也会发生改变。 这也是由于摩擦。 在这样的情况下, 设备更有效率的是, 热能会减少。 一些新设备的效率非常低, 这些设备有“ 能源星” 标签。 您可以在图中看到一个能源星标签。 这些标签告诉我们, 应用效率高, 并减少能源的使用 。The U.S. government’s Energy Star program certifies the energy efficiency of appliances. Look for this label to identify those that are energy efficient. Lesson Summary
::经验教训摘要- Forms of energy include mechanical, chemical, electrical, nuclear, thermal, electromagnetic, and sound energy. These forms of energy can occur as either kinetic or potential energy.
::能源形式包括机械、化学、电气、核、热能、电磁能和音响能,这些形式能源既可以是动能,也可以是潜在能。
- Energy often changes from one form to another. Any form of energy can change into any other, and one form may change into two or more different forms. Energy is always conserved when it changes form.
::能源常常从一种形式变化到另一种形式。 任何形式的能源都可以改变为另一种形式,一种形式可以改变为两种或两种以上不同的形式。 能源在改变形式时总是受到保护。
Lesson Review Questions
::经验回顾问题Recall
::回顾- Define mechanical energy.
::界定机械能源。
- Give an example of chemical energy.
::举一个化学能源的例子。
- What is electrical energy?
::什么是电能?
- Name two processes that release nuclear energy (Advanced Topic).
::列出释放核能的两个程序(高级专题)。
Apply Concepts
::应用概念- If you were on the moon, no sound energy would be able to reach your ears. Explain why. ( Hint: The moon has no atmosphere.)
::如果你们在月球上,那末,任何声音的能量,都不能达到你们的耳朵,你们应当解释一下。
- State how energy is converted by the following electrical devices: light bulb, alarm clock, hair dryer.
::说明下列电气装置是如何转换能量的:灯泡、闹钟、吹风机。
Think Critically
::仔细仔细思考- Relate the thermal energy of an object to the object’s atoms.
::将物体的热能与物体的原子相对应。
- Identify different forms of energy.
