问题 多选题

“静止”在赤道上空的地球同步气象卫星能把广阔视野内的气象数据发回地面,为天气预报提供准确、全面和及时的气象资料.设地球同步卫星的轨道半径是地球半径的n倍,下列说法中正确的是(  )

A.同步卫星的运行速度是地球赤道上物体随地球自转的速度的n倍

B.同步卫星的向心加速度是地球表面重力加速度的

1
n

C.同步卫星运行周期是近地卫星的n3

D.同步卫星运行速度是第一宇宙速度的

1
n

答案

A、同步卫星与地球赤道上的物体具有相同的角速度,根据v=rω知,同步卫星的运行速度是地球赤道上物体随地球自转的速度的n倍.故A正确.

B、根据G

Mm
r2
=ma,则同步卫星的加速度a=
GM
r2
,地球表面的重力加速度g=
GM
R2
,则同步卫星的向心加速度是地球表面重力加速度的
1
n2
倍.故B错误.

C、根据G

Mm
r2
=mr
4π2
T2
得,T=
4π2r3
GM
,所以同步卫星的周期是近地卫星周期的
n3
倍.故C错误.

D、根据G

Mm
r2
=m
v2
r
得,v=
GM
r
,则同步卫星运行速度是第一宇宙速度的
1
n
倍.故D正确.

故选AD.

阅读理解

Still seeking a destination for your weekend break? There are some places which are probably a mere walk away from your college.

King's Art Centre

A day at the Centre could mean a visit to an exhibition of the work of one of the most interesting contemporary artists on show anywhere. This weekend tees the opening of an exhibition of four local artists.

You could attend a class teaching you how to 'learn from the masters' or get more creative with paint ---- free of charge.

The Centre also runs two life drawing classes for which there is a small fee.

The Botanic Garden

The Garden has over 8,000 plant species; it holds the research and teaching collection of living plants for Cambridge University.

The multi-branched Torch Aloe here is impressive. The African plant produces red flowers above blue-green leaves, and is not one to miss.

Get to the display house to see Dionaea muscipula, a plant more commonly known as the Venus Flytrap that feeds on insects and other small animals.

The Garden is also a place for wildlife-enthusiasts. Look for grass snakes in the lake. A snake called 'Hissing Sid' is regularly seen lying in the heat of the warm sun.

Byron's Pool

Many stories surround Lord Byron's time as a student of Cambridge University, Arriving in 1805, he wrote a letter complaining that it was a place of "mess and drunkenness". However, it seems as though Byron did manage to pass the time pleasantly enough. I'm not just talking about the pet bear he kept in his roans. He spent a great deal of time walking in the village.

It is also said that on occasion Byron swam naked by moonlight in the lake, which is now known as Byron's Pool. A couple of miles past Grantchester in the south Cambridgeshire countryside, the pool is surrounded by beautiful circular paths around the fields. The cries of invisible birds make the trip a lovely experience and on the way home you can drop into the village for afternoon tea. If you don't trust me, then perhaps you’ll take it from Virginia Woolf- ----over a century after Byron, she reportedly took a trip to swim in the same pool.

小题1:As mentioned in the passage, there is a small charge for_____.

A.attending the masters' class

B.working with local artists

C.learning life drawing

D.seeing an exhibition小题2:"Torch Aloe" and "Venus Flytrap" are_____.

A.common insects

B.impressive plants

C.rarely-seen snakes

D.wildlife-enthusiasts小题3:We can infer from the passage that Byron seemed_____.

A.to fear pet bears

B.to like walking

C.to be a heavy drinker

D.to finish university in 1805小题4:In the passage Byron's Pool is described as a lake_____.

A.surrounded by fields

B.owned by Lord Byron

C.located in Grantchester

D.discovered by Virginia Woolf小题5:What is the passage mainly about?

A.Some places for weekend break

B.A way to become creative in art.

C.The colourful life in the countryside.

D.Unknown stories of Cambridge University.

单项选择题