英语听力文摘 English Digest 280、飞盘为何会飞？
时间：2019-03-09 作者：英语课 分类：英语听力文摘 English Digest
Why Frisbees Fly
With a gentle flick 2 of the wrist on a warm summer day, you can launch a frisbee 1 on a long and graceful 3 flight. Why do they fly so well? One reason is something called gyroscopic force. This is the tendency of a spinning object to maintain a stable orientation 4. If you throw any round object so it spins as it flies–a record album or compact disk(光盘) for example–it will tend to fly something like a frisbee. If you throw it horizontally, it will stay horizontal for most of its flight. The leading edge of a CD or record is much narrower than its broad, flat surfaces, so this steady orientation helps reduce air friction 5.
Frisbees and compact discs have the same advantages as far as gyroscopic force is concerned, but there’s another physical property that gives your frisbee an aerodynamic edge over your music collection. The top surface of a frisbee is curved. It’s wider in the middle and tapers 6 at the edges somewhat like the wing of an aircraft. This is no accident. Air moves more quickly over a curved surface than over a flat one, and this faster moving air above your frisbee has lower air pressure than the slow moving air beneath it. The higher pressure on the frisbee’s bottom pushes gently upward for a longer flight, an effect known as “lift.”
You can even use lift to make your frisbee fly a curving path. Throw the frisbee not horizontally, but at a slight angle. The lift will push the disk in the direction the curved surface is pointing. Use a sharp enough angle, and the frisbee will swing back toward you like a boomerang!
- We always go to the park on weekends and play Frisbee.我们每个周末都会到公园玩飞盘。
- The frisbee is a light plastic disc,shaped like a plate.飞盘是一种碟形塑料盘。
- He gave a flick of the whip.他轻抽一下鞭子。
- By a flick of his whip,he drove the fly from the horse's head.他用鞭子轻抽了一下，将马头上的苍蝇驱走。
- His movements on the parallel bars were very graceful.他的双杠动作可帅了!
- The ballet dancer is so graceful.芭蕾舞演员的姿态是如此的优美。
- Children need some orientation when they go to school.小孩子上学时需要适应。
- The traveller found his orientation with the aid of a good map.旅行者借助一幅好地图得知自己的方向。
- When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
- Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。