已知地球半径为R，质量为M，自转角速度为（ ，万有引力恒量为G，地球同步卫星距地面高度为h，则（ ）
A．地面赤道上物体随地球自转运动的线速度为（R
B．地球同步卫星的运行速度为（h
C．地球近地卫星做匀速圆周运动的线速度为
D．地球近地卫星做匀速圆周运动的周期大于
AC
题目分析：地面赤道上物体随地球自转的角速度等于地球自转的加速度，半径等于地球半径R，根据
可求地面赤道上物体随地球自转运动的线速度为（R，所以A正确；地球同步卫星的轨道半径为R+h，所以其线速度为
，所以B错误；地球近地卫星的线速度，根据
可求
，所以C正确；
，得，所以地球近地卫星的角速度大于同步卫星的角速度，故也大于地球自转的角速度，再根据
可知，地球近地卫星做匀速圆周运动的周期小于
，所以D错误。
 What brings a nation together? Of the four choices — shared values, language, history, and religion, it’s shared values. In our latest poll (民意调査), seven out of 16 countries chose values as the greatest factor (因索）bringing a nation together, and six preferred language. Both choices scored high in the poll, suggesting that our values and how we express them are closely linked Still, history was not forgotten in some countries, particularly in Mexico and Russia. Even Canada and the United States chose national histories as the second-most important factor uniting their people. The biggest surprise? Not one country picked religion as its top choice.
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