字幕列表 影片播放 列印英文字幕 Now we all know it's boring to just hear laws and rules about energy, so let's get our hands dirty with a good story. It starts when radiant energy from the sun reaches the earth's atmosphere. We know that it gets hotter and some of that energy is used by plants for photosynthesis. Then the plants photosynthesise and turn the radiant energy into glucose, which is chemical energy. The lettuce starts getting bigger but you're hungry, so you pick the lettuce. And since your body is warm from the radiant energy in the atmosphere, and all the lettuce picking, you decide to have something cold for lunch: a salad! The chemical energy that is still stored in the lettuce is transferred to your body. Now you feel strong! So you decide to get on your bicycle and go for a ride. As you pedal, the chemical energy from the lettuce turns into kinetic energy in your legs, causing the bicycle to move. Some of the kinetic energy is converted to thermal energy, which is why you get warm after pedaling for a while. After converting all this chemical energy into kinetic and thermal energy, you return home. It's simple. Energy is moving from the sun, to the lettuce, to your body and then used to pedal the bicycle. But when you get home, it's dark already, so you turn on your dynamo. The dynamo, or generator, produces electrical energy to power your house as well as thermal energy to warm you up. Some of that electrical energy will then be used when you turn on your stove to cook dinner. The electrical energy is then converted to thermal energy to cook your food. So as you can see, the flow of energy keeps going on and on, with energy converting between different forms throughout a regular day. Even as you watch this, you are using chemical energy that you accumulated from everything you ate today. It's a never-ending process! And that's an example of how energy is converted between different forms. So the next time you do a series of actions think about how energy is being converted. You'll be amazed at what you discover!