m/R^2 = mg , 推出 GM = g*R^2
在飞船轨道上,有万有引力里等于向心力
GMm/(R+H)^2 = mV^2/(R+H) , 将GM = g*R^2带入
得到 动能E = 0.5mV^2 = 0.5mgR^2/(R+H)