问题 填空题

一个物体做匀加速直线运动,其有关数据记录在下列表格中,其中遗漏了几项,请你把遗漏的数据补齐,表中①、②、③为空缺,则分别是______、______、______.

时间1秒末2秒末3秒末4秒末
速度(ms-1359
位移(m)212

答案

根据v=v0+at得,v0+a=3m/s,根据x=v0t+

1
2
at2得,x=v0+
1
2
a
=2m,解得v0=1m/s,a=2m/s2

则3s末的速度v3=v0+at3=1+2×3m/s=7m/s,2s末的位移x2=v0t2+

1
2
at22=1×2+
1
2
×2×4m=6m.4s末的位移x4=v0t4+
1
2
at42=1×4+
1
2
×2×16m
=20m.

故答案为:7,6,20.

选择题
单项选择题

Until the late 1940s, when television began finding its way into American homes, companies relied mainly on print and radio to promote their products and services. The advent of television (1) a revolution in product and service. Between 1949 and 1951, advertising on television grew 960 percent. Today the Internet is once again (2) promotion. By going online, companies can communicate instantly and directly with prospective customers. (3) on the World Wide Web includes advertising, sponsorships, and sales promotions (4) sweepstakes, contests, coupons, and rebates. In 1996 World Wide Web advertising revenues (5) $ 300 million.

Effective online marketers don’t (6) transfer hard-copy ads to cyberspace. (7) sites blend promotional and non-promotional information indirectly delivering the advertising messages. To (8) visits to their sites and to create and (9) customer loyalty, companies change information frequently and provide many opportunities for (10) .

A prototype for excellent (11) promotion is the Ragu Web site. Here visitors can find thirty-six pasta recipes, take Italian lessons, and view an Italian film festival, (12) they will find no traditional ads. (13) subtle is the mix of product and promotion that visitors hardly know an advertising message has been (14) . Sega of America, maker of computer games and hardware, uses its Web site for a (15) of different promotions, such as (16) new game characters to the public and supplying Web surfers the opportunity to (17) games. Sega’s home page averages 250,000 visits a day. To heighten interest in the site, Sega bought an advertising banner on Netscape (18) increasing site visits by 15 percent. Online (19) in Quaker Oats’ Gatorade promotion received a free T-shirt in exchange for answering a few questions. Quaker Oats reports that the online promotion created product (20) and helped the company know its customers better.

2()

A.transferring

B.transforming

C.transmitting

D.transplanting