我们试着用力蹦起来,看看究竟能蹦多高?身体重量也就几十千克,蹦到空中却很费力;要举起相当于自身体重的物体,多数人恐怕做不到。但是,金属制造的庞大的飞机却能在天上自由飞行,要知道飞机的重量大都是以吨计量的,如新近服役的A380客机起飞重量可达560吨,是什么力量把它托举在空中呢?实际上,举起飞机的是气流,不是我们把纸片用嘴吹上天空那样,而是从前向后平吹的气流。平吹的气流为什么能把飞机那样的金属庞然大物托举在空中?这就要用到流体动力学。空气是一种接近理想的流体,适用于所谓的伯努利方程,它是荷兰的物理学家丹尼尔·伯努利在1726 We tried hard to jump up and see how much can jump? Body weight is tens of kilograms, jumped into the air is very laborious; to lift the equivalent of their own body weight, most people probably can not do it. However, the huge metal-made aircraft can fly freely in the sky, knowing that the weight of the aircraft is mostly measured in tons. For example, the newly-started A380 passenger aircraft take-off weight of 560 tons. What force lifts it in the air? In fact, it is the air flow that lifts the airplane, not the air flow that blows the paper flat against the sky with the mouth of the paper. Why can flat air blown up in the air like a metal monster? This requires the use of fluid dynamics. Air is a nearly ideal fluid for the so-called Bernoulli equation, which was discovered by the Dutch physicist Daniel Bernoulli in 1726