题目

某次龙卷风发生时，房屋外部气压会减小到9×104Pa，假如屋内气压为1×105Pa，屋顶面积为100m2  ， 求：   （1）说明房屋外部气压减小的原因；    （2）房屋内外的压强差；    （3）屋顶受到的压力及此压力的方向． 答案：房屋外部气压减小的原因是房屋外部空气流速较大，压强减小    房屋内外的压强差为10000Pa    屋顶受到的压力为106N，此压力的方向向上    【解析】 （1）龙卷风刮过时，房屋外部空气流速较大，压强减小． （2）房屋内外的压强差： （3）由可得，屋内外的大气压力差 由于房屋外部靠近龙卷风的阅读下面题文，根据证判音标，或者所险单训的提示，在够个空格内填入一个恰当的间，要求所填的调意义准确，形式正确，使短文意思完整，行文连期。As everyone knows, Jingdezhen in Jiangxi province is the center of world porcelain production（瓷器生产）.The【1】[lkl] porcelain is quite popular around the world. Last week my school held a two-day research activity, the aim of which was to build students' awareness(意识）of traditional Chinese 【2】 [klt(r)].On our way to Jingdezhen, our guide 【3】(introduction)us to the basics of porcelain production. Our first stop was the Museum of Chinese Ceramics, which has a unique collection of porcelain made from 【4】such as clay and stone.The guide told us of the great achievements in ceramics from ancient times until today. I paid special 【5】to what he said, and I learned that ceramics was invented in the Neolithic（新石器时代）period. At that time, clay was【6】 (use) to make pottery (陶器）,which carried water and food. Today, we still use porcelain but our pottery is far more beautiful than the【7】(produce) of those times.In the afternoon, we visited a factory to learn about the【8】[prses] of making ceramics. We found that any small mistake can【9】to the failure.On the second day, we were given some clay and the chance to design a piece of pottery. Although our efforts were not as beautiful as the articles in the museum, they were our own work.The two-day activity was very【10】(enjoy) and meaningful. I learned a lot about porcelain and made an item on my own. It meant a lot to me.