问题 选择题

某星球的质量是地球质量的

1
2
,其半径是地球半径的
1
3
,该星球表面的重力加速度是地球表面重力加速度的(  )

A.

1
2

B.

1
3

C.

2
9

D.

9
2

答案

设任一天体的质量为M,半径为R,质量为m的物体在天体表面时,天体对物体的万有引力近似等于物体的重力,则有

   mg=

GMm
R2

得g=

GM
R2

则得星球表面的重力加速度与地球表面重力加速度之比为

  g:g=

GM
R2星
GM
R2地
=9:2,即星球表面的重力加速度是地球表面重力加速度的
9
2
倍.

故选D

阅读理解

阅读理解。

    There is a special kind of hotel in Quebec, Canada. It has a bar, a church, a shop and a small theater.

These things are not unusual. But this hotel is only open from January till March every year. Why? Because it is made of ice and snow! When the weather gets warm, the hotel melts(融化) and closes. Every winter,

the hotel owners build the hotel again.

    Everything in the Ice Hotel is made of ice and snow. All the furniture, such as the tables and chairs, is

made of ice. Even the beds are made of ice! So people use special sleeping bags on the ice beds. Inside

the ice hotel, the temperature is about 27°F(-3°C)

    When people sleep, the sleeping bags keep them warm. In the morning, they can have a hot breakfast. After breakfast, people can enjoy winter activities. They can go skiing or ice fishing. Or they can go skating in the dining room. At the end of the day, people can relax at the bar.They can have drinks in glasses made of ice.

    Many people enjoy the Ice Hotel every year. But they can only enjoy it for a short time before it melts

again.

1. Every year, this hotel is only open for      _   

A. four weeks  

B. about three months  

C. two seasons  

D. about a year

2. People can go ___     in the dining room after breakfast.

A. skiing.      

B. skating         .  

C. fishing      

D. swimming

3. What's the best title of this passage?

A. An Unusual Hotel  

B. A Warm Hotel  

C. A Common Hotel  

D An Old Hotel

填空题