15.4 特定热量
Section outline
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This girl and her brother are having fun at the beach. It’s a warm, sunny day, and the sand feels hot on their bare feet. They take a dip in the water whenever they want to cool off because the water feels much cooler than the sand. Why does the sand—but not the water—get hot in the sun? The answer has to do with specific heat.
::这个女孩和她哥哥在海滩上玩得很开心。 这是一个温暖、阳光明媚的天气,沙子在赤脚上感到热。 他们想冷却就浸泡在水里,因为水比沙凉得多。 为什么沙子 — — 而不是阳光下热水 — — 却在太阳下热?答案与特定的热量有关。Be Specific
::具体具体Specific heat is a measure of how much it takes to raise the of a substance. It is the amount of necessary to raise one mass unit of that substance by one temperature unit. In the SI system, specific heat is measured in J/kg•K. (Occasionally, you may also see specific heat expressed sometimes in J/g•K). Specific heat is a property that is specific to a given type of matter. That’s why it’s called specific .
::特定热量是测量一种物质加热量的尺度。 具体热量是用一个温度单位将该物质提升成一个质量单位的必要数量。 在SI系统中,特定热量用J/kkk / k. K. 测量( 实际中, 你也可以看到有时以J/ g. K. 表示的特定热量 ) 。 特定热量是特定物质类型所特有的特性。 这就是为什么它被称为特定物质的原因。Variation in Specific Heat
::特定热量变化The Table compares the specific heat of four different substances. such as iron have low specific heat. It doesn’t take much energy to raise their temperature. That’s why a metal spoon heats up quickly when placed in a cup of hot coffee. Sand also has a relatively low specific heat. Water, on the other hand, has a very high specific heat. It takes a lot more energy to increase the temperature of water than sand. This explains why the sand on a beach gets hot while the water stays cool. Differences in the specific heat of water and land even affect climate.
::表格比较了四种不同物质的具体热量,例如铁的热量低,提高温度不需要多少能量。这就是为什么金属勺子放在热咖啡杯里会很快热起来的原因。 沙子也有相对低的热量。 另一方面,水有非常高的热量。 增加水温需要比沙子多得多的能量。 这解释了为什么沙子在沙滩上热,而水却保持凉爽。 水和土地的具体热量差异甚至影响气候。Substance Specific Heat (J/kg•K) iron 450 sand 670 wood 1760 water 4180 Q: Metal cooking pots and pans often have wooden handles. Can you explain why?
::问题:金属锅和锅往往有木柄。你能解释为什么吗?A: Wood has a higher specific heat and lower thermal conductivity than metal, so it takes more energy to heat a wooden handle than a metal handle, and that heat conducts slower through the wood. As a result, a wooden handle doesn't heat up as quickly as a metal pan and is less likely to burn your hand when you touch it.
::A:木头比金属的热度更高,热导导力也较低,因此木制把手的热度要高于金属柄的热度,而木材的热度要慢一些。因此,木制把手的热度不会像金属锅那样快,触摸时也不太可能烫伤你的手。Q: Why does hot tea cool down faster than hot soup?
::问:为什么热茶比热汤凉快?A: Soup has a higher specific heat than tea, which means it can absorb more heat without a significant increase in temperature. Consequently, when cooling down, the hot soup has to lose more heat to the environment than the hot tea to experience the same decrease in temperature. This is why the soup retains its heat for a longer period and cools down more slowly, while the tea, having a lower specific heat, loses its heat more quickly and therefore cools down faster.
::A:汤的热量比茶叶的热量要高,这意味着它可以吸收更多的热量,而不会大幅升高温度。因此,当冷却时,热汤对环境的热量必须比热茶少得多,才能经历同样的温度下降。 这就是为什么汤的热量保持更长的一段时间,冷却得更慢,而茶的热量更低,热量更快,因此冷却得更快。Summary
::摘要-
Specific heat is the amount of heat energy necessary to raise one mass unit of a substance by one temperature unit.
::特定热量是用一个温度单位将物质的一个质量单位提升到一个物质所需的热能量。 -
In the SI system, specific heat is measured in J/kg•K.
::在SI系统中,用J/kg/KK测量特定热量。 -
Specific heat is a property that is specific to a given type of matter, and substances vary in their specific heat. Metals tend to have low specific heat. Water has very high specific heat.
::特定热是特定物质类型特有的特性,物质在特定热量方面各有不同,金属的热量往往较低,水的热量非常高。
Review
::回顾-
What is specific heat?
::什么是特定热量? -
Water in a lake always warms up in the summer more slowly than the adjacent land. Use the concept of specific heat to explain why.
::湖中的水在夏天总比附近的土地更慢。 使用特定热的概念来解释原因。
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Specific heat is the amount of heat energy necessary to raise one mass unit of a substance by one temperature unit.