历史上,牛顿发现万有引力的存在,曾有人戏言是苹果“砸”在他头上而发现的,而他关于人造卫星的草图也是在大家熟悉的情景下推演出来的。即在高山上水平抛出物体,初速度越大,抛的越远,当仍出的速度足够大,重物将永不下落绕地球做匀速圆周运动成为一颗人造地球卫星。重物总是向下 Historically, Newton's discovery of the existence of gravitation has been the subject of jesting by Apple on his head, and his sketches of artificial satellites are also deduced in familiar situations. That the level of the object thrown in the mountains, the greater the initial velocity, throwing farther, when still large enough speed, heavy objects will never fall around the Earth to do a uniform circular motion to become an artificial Earth satellite. The weight is always down