【题目】我国发射的宇宙飞船在完成任务后,返回地面指定地点,宇宙飞船在下落到地面附近时,由于空气阻力作用做匀速直线运动,则宇宙飞船在匀速下降的过程中,它的( )
A.动能不变,势能减小,内能增大
B.动能不变,势能增大,内能减小
C.动能减小,势能不变,内能增大
D.动能增大,势能减小,内能不变
【答案】A
【解析】试题分析: 我国发射的宇宙飞船在完成任务后,返回地面指定地点,宇宙飞船在下落到地面附近时,由于空气阻力作用做匀速直线运动,则宇宙飞船在匀速下降的过程中,由于它是匀速运动的所以,动能是不变的。飞船的高度在减小,所以势能变小。飞船和空气有摩擦,在下落的过程中机械能会转化为内能。
A.动能不变,势能减小,内能增大 符合题意;
B.动能不变,势能增大,内能减小 不合题意;
C.动能减小,势能不变,内能增大 不合题意;
D.动能增大,势能减小,内能不变 不合题意;
故选A。
考点:本试题考查的是机械能的转化。动能是物体由于运动而具有的能量,动能跟物体的质量和物体运动的速度有关。势能跟物体的质量和物体被提升的高度有关。
科目:初中地理 来源: 题型:
【题目】根据句子意思,用括号中所给单词的正确形式填空。(每空限填一个单词)
【1】Suddenly, a pile of _____________ (leaf) were blown into the house.
【2】Tom's ideas and ____________ (I) jump together on this matter. Great minds always think alike!
【3】The boat floated _______________ (danger) near the waterfalls.
【4】I've found a great cafe--good coffee and a_______________ (friend) environment.
【5】Car drivers should give way to the walkers on the _________________ (cross).
查看答案和解析>>
科目:初中地理 来源: 题型:
【题目】选用方框内的单词或词组填空,其中有一个单词或词组是多余的。
frozen a bit stream bet calm down shade
【1】There was a small ______________ at the end of the garden. Kids often played in the water.
【2】You did quite well. I_____________ you were good at this game when you were young.
【3】At home_____________ food has to be stored at a very low temperature to keep longer.
【4】Every time I take an exam, I always tell myself: __________ and try your best!
【5】The weather is _____________ unusual these days. It used tobe very cool at this time of year.
查看答案和解析>>
科目:初中地理 来源: 题型:
【题目】根据首字母提示完成单词。
【1】 Many people lost their lives in the w_________.
【2】 The music sounds so s_________, which makes us relaxed.
【3】 In his s_________ time, he often goes swimming with his brother.
【4】 Judy is the pride of her family. She has never let her parents d_________.
【5】 I_________ people can’t be led by the nose.
查看答案和解析>>
科目:初中地理 来源: 题型:
【题目】阅读对话,回答下列问题。
甲:“我的名字叫赤道” 乙:“我的名字叫本初子午线”
【1】关于甲、乙长度的叙述,正确的是( )
A. 甲与乙的长度相同 B. 甲的长度约6371千米
C. 乙的长度约4万千米 D. 甲的长度是乙的两倍
【2】下列叙述与乙相吻合的是( )
A. 指示东西方向 B. 以东是东经,以西是西经
C. 以北是北纬,以南是南纬 D. 以东是东半球,以西是西半球
查看答案和解析>>
科目:初中地理 来源: 题型:
【题目】书面表达
假如你叫李涛-你和父母就“学牛周末该不该与同学外出活动”进行了讨论。请以Should teenagers go out with friends at weekends?为主题,参照表中所提供的信息,给你的网友Sam写一封邮件,介绍讨论情况。
Your parents' ideas | Your ideas |
1读书、做作业 | 1和同学外出活动 |
2好好上床休息一下 | 2外出活动也是一种调节和放松 |
3考试分数最重要 | 3…… |
4帮助父母做家务活 | 4…… |
要求:1所写内容要包括表内信息:
2表中Yourideas中的3、4两个观点由你对应做出合理的说明,还可适当发挥你父母和你的其他观点。
3词数为110词左右。信的开头和结尾已给出,不计入总词数。
Dear Sam,
How is everything going with you? I have had a discussion with my parents recently. We talked about if teenagers should go out with friends at the weekends.
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
What's your idea about the problem?
I'm looking forward to your reply.
Yours,
Li Tao
查看答案和解析>>
科目:初中地理 来源: 题型:
【题目】 Choose the best answer(根据短文内容,选择最恰当的答案)
Wales is a country that is part of Britain. Like all countries, it has a national flag. The flag is
made of two thick lines –green below, white on top. On its own that would like very boring, but the
flag of Wales is rather memorable. It also has a drawing of a fierce, blood-red dragon with wings, a
raised front leg and arrows for its tail and tongue.
Visit Wales and you will see this dragon flying proud above public and private buildings. You
will spot it at the top of Welsh government letters, and even on bar signs. Thousands of Welsh
business contain the words“Red Dragon”in their names –from small cafes to huge shopping malls. Much more interesting, however, is the story behind the dragon. It comes from the country’s old and colorful folk tales.
The Mabinogion is one of the oldest pieces of literature in Britain. In one of its stories, there is a fierce struggle between a red dragon and a white dragon. The cries of pain from the red dragon are a terrible thing. They are so horrific that they cause animals to die when they hear them. King Klud of Britain catches the two dragons, then he transports them to Snowdonia, the site of a tall mountain in Wales.
In another story, King Vortigern tries to build a castle on the site where the dragons are buried(埋葬), but the building is destroyed each night. It is a mystery to the King, who doesn’t know the dragons are there. A young magician tells the King about the dragons, who then sets them free. The two dragons continue their fight until the red dragon wins. This story made the red dragon an obvious choice for a national symbol.
There are other symbols of Wales, but it is the red dragon that means the most to Welsh people –and has the best stories.
【1】We cannot see ______ in Wale’s national flag.
A. a horrible dragon B. three arrows
C. a thick white line D. a thick green line
【2】The underlined word spot in the second paragraph probably means _______.
A. meet B. receive C. write D. see
【3】The main idea of the second paragraph is that ______.
A. the red dragon is very popular in Wales
B. we can usually find the dragon on top of buildings
C. businessmen like using the red dragon as their logo
D. the old colorful folk tales make the red dragon a national symbol
【4】_______ is the superhero in the tales.
A. the young magician B. King Liud
C. King Vortigern D. Snowdonia
【5】From the tales, we can know that _______.
A. the dragons destroy the castle because they didn’t like the castle
B. the dragons fight against each other underground.
C. the red dragon is the winner in different tales
D. animals die when they hear the two dragons
【6】The best title for this story is ________.
A. Wales’ National flag B. Wales’ colorful folk tales
C. The symbols of Whales D. Wale’s red dragon
查看答案和解析>>
科目:初中地理 来源: 题型:
【题目】根据句意及汉语提示完成单词。
【1】They pay a_________(每周的)visit to their grandparents.
【2】The car is not mine.I think it may be one of the_________(导演).
【3】Do you like watching_____________ (喜剧)or horror films?
【4】The concert will be c_________ live in TV tomorrow.
【5】Could you offer me some____ (最新的)information? I need to write an important article.
查看答案和解析>>
湖北省互联网违法和不良信息举报平台 | 网上有害信息举报专区 | 电信诈骗举报专区 | 涉历史虚无主义有害信息举报专区 | 涉企侵权举报专区
违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com