题干

如图所示,一高为40cm,内壁光滑,导热性能良好的薄气缸竖直放置,厚度不计的活塞质量为m=2kg,横截面积为S=1×10﹣3m2,气缸的顶部A点处有一个漏气孔,稳定时活塞的下端封闭有温度为T=300K,长度为30cm的气体柱,已知大气压强恒为P0=1.0×105Pa.g=10m/s2.求:

①稳定时被密封气体的压强;

②缓慢将气缸内的密封气体加热到500K时,被密封的气体的压强.

上一题 下一题 0.0难度 选择题 更新时间:2017-08-07 12:01:45

答案(点此获取答案解析)

解:①设稳定时被密封气体的匀强为p1,则有:

P1S=P0S+mg

得p1=p0+ mgs

同类题2

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    All languages change over time, but some change at a faster rate than others. ____ The most important factors are the number of people who speak a language, where they live and whether they move around, the importance of the language for world trade and communication, and changes in technology.

    ____ However, today English is the most widely used language in the world. English is spoken by about 350 million people as a first language in countries such as Great Britain, the United States. In addition, about a billion more people speak English as a second language.

    English started to take over French as an international language during the period of British colonialism (殖民主义) when the English ruled many countries in Africa and Asia. ____ The colonial period came to an end at the same time that several other changes occurred. For example, the U.S. started to play a greater part in global affairs and the international economy. New means of communication technology such as television and the Internet spread English worldwide. ____ In addition, they could use the Internet for information, business, or e-mail communication, all in English. Just as the use of English spread, other languages changed English by contact or by new inventions and technology.

    In contrast, Icelandic is a language that has changed very slowly. Icelandic speakers today can understand poetry written in a slightly different dialect over 1,000 years ago! Why has Icelandic changed so slowly? The main reason is the isolated (孤立的) location of the island in the middle of the Atlantic Ocean. ____ Compared to England, Iceland had no history of colonialism. Iceland's small population has not played a major role in international trade or communication. Today, most Icelanders speak English in addition to their native language. With outside influences, Icelandic is changing more rapidly now.

A. People everywhere could watch the news or sports events in English.

B. These changes have a great influence on the development of society.

C. Isolation meant that for hundreds of years, Icelanders had little contact with speakers of other languages.

D. What are some of the factors that influence how quickly a language changes?

E. The language communication brings about the communication of technology.

F. In the past, other languages such as Latin or French were more important than English.

G. English was the primary means of communication in these colonies.