五、跨学科 物理 阅读理解。
主题群:科学与技术 子主题:科学原理 语篇类型:说明文 难度:★★★
Slides are simple but always fun. All you need to do is climb up to the top and slide down. But do you know that there is science behind the simple playground equipment(设备)?
Isaac Newton said what goes up must come down. He was talking about gravity(重力). Slides work because of gravity. But that is not all.
① You climb up the slide and sit down.
You are ready to go. Are you sliding down? No, not yet. Things stay still(静止的) unless something makes them move. It is Newton's first law of motion. So you have to give yourself a push to start the journey down.
② Now you are sliding down.
Do you feel you are slowing down a bit? When two things rub(摩擦) against each other, they cause friction(摩擦力). Without friction, you will slide down faster and faster to the bottom.
③ At the bottom of the slide, you come to a full stop.
Your feet touch the ground and add extra friction. Newton's first law of motion also says moving things keep moving unless something makes them stop. So, if you do not use your feet, you'll fly off the slide.
1.（创新考法·行文方式）How does the writer start the text?
A. By giving a fact. B. By giving an example. C. By telling a story. D. By asking a question.
2.（创新考法·图片理解）Which picture explains why you slow down a bit when sliding down?
3. What is the best title for the text?
A. Fun with a slide B. Science behind a slide
C. Newton's first law of motion D. Secrets of gravity
