“嫦娥一号”在距离月球表面高为h处绕月球作匀速圆周运动，已知

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问题问答题

“嫦娥一号”在距离月球表面高为h处绕月球作匀速圆周运动，已知月球半径为R，月球表面的重力加速度为g，求：“嫦娥一号”环绕月球运行的周期为多少？

答案

（1）绕月卫星绕月球做匀速圆周运动，根据万有引力提供向心力，设卫星的质量为m、轨道半径为r、月球质量为M，有

(R+h)2

=m(

2π

)2(R+h)

地球表面重力加速度公式

=mg

联立①②得到

T=2π

(R+h)3

gR2

答：“嫦娥一号”环绕月球运行的周期为T=2π

(R+h)3

gR2

阅读理解

第三节：阅读理解（共20小题，每题2.5分，满分50分）

阅读下列短文，从每题所给的四个选项中，选出最佳答案

A couple of years ago, I received a $ 600 insurance dividend (保险股息).Sitting at the kitchen table, my wife and I discussed what we might do with the money. I realized now that the refrigerator overheard our talk. The very next day it went wrong. The repairman told us we needed a new unit. Cost:$600. Not long after that, we got a refund（赔偿金）from the shop, enough to pay for a trip to Mexico. “I’ve something to tell you,” I said to my wife in a low voice. “How about the living-room?” she suggested. I remembered the color TV set was there. “No, not there. Let’s go out.” I showed her the check as we stood on the driveway. We held each other excitedly and hardly noticed the rain. My car was parked within5 meters. I didn’t think anything about it at the time. As I started for the airport the next day, the car began making strange sounds. Changing the engine cost about $ 1, 000.

Then I looked through our financial records. I discovered that during the last ten years we spent all our “found money” repairing a hot water heater, a television and a stove.

I never mention money in front of our mechanical equipment. But if this article is published and I am paid for, the word processor（文字信息处理机）is going to go for sure. It’ll know.