题目

一颗人造地球卫星离地面的高度为h，卫星绕地球做匀速圆周运动，已知地球半径为R，地球表面重力加速度为g，引力常量G已知．求：                                                                                                           （1）第一宇宙速度的表达式；                                                                                     ______ all the texts that are written,stored, and sent electronically, a lot of them are still ending up op paper.A．ForB．FromC．AlthoughD．By