题目内容

一辆质量为4t的载重汽车，在平直的公路上以90km/h的速度匀速行驶，汽车受到的阻力为车重的0.069倍．(g=10N/kg) 求：汽车有四个轮子，每个轮子与地面的接触面积约为250cm2，汽车对地面的压强多大

查看答案

搜索结果不匹配？点我反馈

更多问题

小明乘坐的汽车在某公路上做匀速直线运动，下表是小明记录的汽车运行各时刻及公路旁边路牌的里程数．从表中数据可知，汽车的速度是______km/h．时刻 10时02分 10时04分 10时06分 10时08分 10时10分里程数 102km 104km 106km 108km 110km

电视机遥控器是利用线来实现对电视机的控制的．有时，我们把遥控器对着电视机周围的光滑墙壁也能实现控制，这是利用光的原理．

Section BPassage One In the first year or so of Web business, most of the action has revolved around efforts to tap the consumer market. More recently, as the Web proved to be more than a fashion, companies have started to buy and sell products and services with one another. Such business-to-business sales make sense because businesspeople typically know what product they’re looking for. However, many companies still hesitate to use the Web because of doubts about its reliability. "Businesses need to feel they can trust the pathway between them and the supplier," says senior analyst Blane Erwin of Forrester Research. Some companies are limiting the risk by conducting online transactions only with established business partners. Another major shift in the model for Internet commerce concerns the technology available for marketing. Until recently, Internet marketing activltie8 have focused on strategies to "pull" customers into sites. In the past year, however, software companies have developed tools that allow companies to "push" information directly out to customers, transmitting marketing messages directly to targeted customers. Most notably, the Point cast Network uses a screen saver to deliver a continually updated stream of news and advertisements to subscribers’ computer monitors. Subscribers can customize the information they want to receive and proceed directly to a company’s Web site. Companies such as Virtual Vineyards are already starting to use similar technologies to push messages to customers about special sales, product offering, or other events. But push technology has earned the contempt of many Web users. Inline culture thinks highly of the notion that the information flowing onto the screen comes there by specific request. Once commercial promotion begins to fill the screen uninvited, the distinction between the Web and television fades. But it is hardly inevitable that companies on the Web will need to resort to push strategies to make money. The examples of Virtual Vineyards, Amazon: com and other pioneers show that a Web site selling the right kind of products with the right mix of interactivity, hospitality, and security will attract online customers. And the cost of computing power continues to fall, which is a good sign for any enterprise setting up shop in silicon. People looking back 5 or 10 years from now may well wonder why so few companies took the online plunge. The purpose of the author in writing the text is to ______.

Section C Unemployment is a deeply (36) sensitive political issue for Chancellor Gerhard Schroeder. Back in 1998 he was (37) for his first term on a promise that the jobless count would be brought down to (38) . He (39) on that and now the official unemployment figure is above five million, the first time since the great depression of the 1930s, which brought the Nazis to power. And to make matters (40) , the official figures may greatly (41) the real extent of the problem. Once those on government training schemes and the like are (42) the actual number of people looking for work could be as high as (43) . The German economy has yet to fully recover from the boom and bust that followed reunification a decade ago. (44) , where work has shifted to new manufacturing centers such as Chine. But, despite the latest unemployment figures, there are some recent signs of economic improvement in what is still by far Europe’s largest economy. (45) . Meanwhile businesses are more optimistic than they were a couple of years ago. Welfare benefits have been reduced. Companies have been re-organized to cut costs. (46) The German economy is growing again: though slowly, and it is seen as one of the more robust in the European Union.