Flying a kite is a common childhood pastime. Even if you haven’t done it yourself, you’ve probably at least seen it. But have you ever stopped and wondered how the fun activity actually works? What is it that keeps that colorful cloth aloft◆?
If your answer to that last question is “the wind,” you are on the right track. It’s much more complicated than that, though. A kite that flutters steadily in the air with little effort from the person holding onto the string is a working example of the basic principles of aerodynamics◆, or the science of flight. Whether you are talking about a kite, a bird, or an airplane, the science is the same. The upward◆ force that pushes a kite into the air and keeps it there is called lift◆. This is achieved when the air pressure underneath◆ the kite, or a wing, is higher than the air pressure above it. That difference in pressure is the result of a difference in air speeds; fast-moving air is lower in pressure and slow-moving air is higher. The design of a kite is angled◆ so that wind passing underneath it is slowed down, resulting in lift. Of course, you have to remember that the kite, though fairly light, still weighs something, so the force of the lift must be equal to a kite’s weight in order for it to fly.
Once you have your kite in the air, then thrust (the force that pushes the kite forward) and drag (the force that pushes back against the kite) come into play. If you want to keep the kite steady, then these two forces must also be equal. Now, grab a kite and give it a try. |
沒有留言:
張貼留言