神舟六号载人飞船在绕地球飞行5圈后变轨，轨道变为距地面高度为h的圆形轨道．已知地球半径为R，地面附近的重力加速度为g．求

万有引力,推力
万有引力,推力

I was very happy when I heard that China's second manned spaceship-Shenzhou Ⅵ was sent up into space
at 9:00 a.m.on Oct.12th,2005.All Chinese people are proud of the two astronauts,Fei Junlong and Nie
Haisheng.
I also knew that computers played an important role during the whole flight.I see how important it is to
master space technology.These two astronauts have set good examples for us.I will study hard and in the
future I want to become an astronaut like Fei Junlong or Nie Haisheng and try to make a contribution to building
our country.
答案不唯一

7.9*90*60=42660

准确的说是 2005-10-12
发射： 北京时间2005-10-12 09:00:00
起飞： 北京时间2005-10-12 09:00:03.583
着陆： 北京时间2005-10-17 04:33

宇宙飞船在圆轨道上运行引力=重力,提供它做圆周运动向心力
mg*=mv²/r ①
(r=(R+h)
mg*=GMm/r² ②
在地球表面 mg=GMm/R² ③
由②③ 得g*r²=gR²
由①得宇宙飞船在圆轨道上运行的速度
v=√(g*r)==√[(gR² /(r+h)]

解题思路：飞船在圆轨道上运行时，由地球的万有引力提供向心力．在地球表面，物体的重力等于万有引力，根据飞船在圆轨道和地球表面两种情况，由牛顿第二定律列式求解其速度和周期．

设地球质量为M，飞船质量为m，圆轨道的半径为r
根据万有引力定律和牛顿第二定律G
Mm
r2＝m
υ2
r
在地面附近 G
Mm
R2＝mg
由已知条件知r=R+h
联立以上三式，求得υ＝R

g
R+h
由T＝
2πr
υ
求得T＝
2π
R

(R+h)3
g
答：飞船在圆轨道上运行的速度为R

g
R+h，运行的周期为
2π
R

(R+h)3
g．

点评：
本题考点： 万有引力定律及其应用．

考点点评： 本题是卫星类型，根据万有引力等于向心力和万有引力等于重力，运用万有引力定律和牛顿第二定律进行求解．

Beijing at 9:09:52 on October 12,2005,China's independently developed Shenzhou-VI manned spacecraft at the Jiuquan Satellite Launch Center,the accurate and entered the preset orbit,the Shenzhou VI manned spacecraft was successfully launched.
Shenzhou-VI manned spaceship is one of China's Shenzhou spacecraft series."Shenzhou VI" and "Shenzhou V" there is no difference in appearance,still propulsion,re-entry capsule,the orbital three-compartment structure,the weight remained at 8 tons,using the LM-II F carrier rocket launch .It is China's second ship carrying astronauts on the spacecraft,but also China's first implementation of a "multi-day" task of the manned spacecraft.
At 21:10 on September 25,2008,carrying Zhai Zhigang,Liu Ming,Jing Haipeng three astronauts of Shenzhou VII spacecraft from the Jiuquan Satellite Launch Center.The arrival of this exciting moment,we are full of pride,joy,the 1.3 billion Chinese people witnessed this historic moment.Chinese astronauts out of the spacecraft into the space,the first step in the door,marking China's space industry has a new beginning.
Development of space activities,taking into consideration a country's comprehensive national strength,but also a high-tech countries in the ability to always maintain the leading position in the field of the key.It fully demonstrated the strength of national science and technology in the development and promotion of aviation and aerospace technology play a crucial role,on behalf of a country's economic and social infrastructure,but also indicates that the country and the nation's development and the future.
The significance of the Shenzhou spacecraft
1 manned spaceflight is a country's comprehensive national strength and important sign of the increasingly powerful.
2 to promote the development of national economy
3 guide scientific and technological progress
4 to protect national security

从2005年10月12日上午9时到2005年10月17日上午9时,恰好5天,24×5=120小时.
2005年10月17日凌晨4时33分到2005年10月17日上午9时,9-4:33'=4：27'
120-4:27'=115:33'=115.55小时
答案：（115.55）小时.

酒泉卫星发射中心

“神舟六号”载人飞船安全着陆。

算式是：7.5÷5=1.5（小时）1.5×30=45（小时）

（1）a=v平方/2s=14平方/(2*14) m/s^2=7m/s^2
(2) t=v/a=14/7=2s
(3)5F-mg=ma
F=m(g+a)/5=8000*(10+7)/5=27200N