#2 - When science gets hot 当科学变得热

1.Fire! Flames! Burning! Heat!
The science of heat is important in all kinds of ways. Not only do we cook with heat, but we also warm our homes and heat water. Burning happens in all kinds of engines in cars, trucks, planes, and rockets. It is also used in factory processes, from making steel to shaping plastics.

V Flames!!! V

2.Heat can move by conduction.
A hot object will pass on, or transfer some of its heat to a cooler one. Dip metal spoon in a hot drink and the spoon handle soon warms up. Heat is conducted from the drink through the metal.

V This is heat moving through a metal rod. V

3.Heat moves by invisible 'heat rays'.
This is called thermal radiation and the rays are infrared waves. Our planet is warmed by the sun because heat from the Sun radiates through space as infrared waves.

4.Burnning, also called combustion, is a chemical process.
Oxygen gas from the air joins to or combines with, the substance being burned. The chemical change releases lots of heat, and usually light too. If this happens really fast, we call it an explosion.

V This is the combustion reaction. V

V And this is an explosion. V

5.Temperature is a measure of how hot or cold something is.
It is usually measured in degrees Celsius (°C) or Fahrenheit (°F). Water freezes at 0°C (32°F), and boils at 100°C (212°F). We use thermometers to take our temperatures. Your body temperature is about 37°C (98.6°F).

V This is a thermometer. V

6.Heat moves through liquids and gases by convection.
Some of the liquid or gas takes in heat, gets lighter, and rises into cooler areas. Then other cooler liquid or gas moves in to do the same and the process repeats. You can see this as a 'wavy' hot air rising from a flame.

火！火焰！燃烧！热！
热科学在各种各样的方面都很重要。我们不仅用热量做饭，还能温暖我们的家园和加热水。燃烧发生在汽车，卡车，飞机和火箭中的各种发动机中。它也用于工厂工艺，从制造钢成型塑料。

V火焰！ V

通过传导可以移动。
一个热的物体将传递，或将一些热量转移到较冷的一个。蘸金属勺子在热饮料和勺子手柄很快加热。饮料通过金属进行热量化。

V这是热量通过金属棒移动。 V

通过看不见的“热射线”移动。
这被称为热辐射，射线是红外波。我们的星球由太阳暖和，因为太阳的热量作为红外波辐射穿过太空。

燃烧也是一种化学过程。
来自空气的氧气与被燃烧的物质连接或结合。化学变化释放大量的热量，通常也会发光。如果这个事情真的很快，我们称之为爆炸。

这是燃烧反应。 V

这是爆炸。 V

温度是衡量某些东西有多热或冷的东西。
通常以摄氏度（°C）或华氏度（°F）为单位。水在0°C（32°F）下冻结，在100°C（212°F）下沸腾。我们使用温度计来摄取我们的温度。您的体温约为37°C（98.6°F）。

V这是一个温度计。 V

热量通过液体和气体通过对流移动。
一些液体或气体吸收热量，变得更轻，并进入较冷的区域。然后其他较冷的液体或气体移动进行相同的过程重复。你可以看到这是一个从波涛汹涌的“波浪”热气。