问题 计算题

(12分)为了最大限度地减少道路交通事故,全国开始了“集中整治酒后驾驶违法行为”专项行动.这是因为一般驾驶员酒后的反应时间比正常时慢了0.1~0.5 s,易发生交通事故.图示是《驾驶员守则》中的安全距离图示(如图所示)和部分安全距离表格.

车速

v(km/h)

反应距离

s(m)

刹车距离

x(m)

停车距离

L(m)

40101020
601522.537.5
80A4060
请根据该图表回答下列问题(结果保留两位有效数字):

(1)请根据表格中的数据计算驾驶员的反应时间.

(2)如果驾驶员的反应时间相同,请计算出表格中A的数据.

(3)假设在同样的路面上,刹车时加速度大小为6.2m/s,一名饮了少量酒的驾驶员驾车以72 km/h速度行驶,在距离一学校门前50 m处发现有一队学生在斑马线上横过马路,他的反应时间比正常时慢了0.2 s,会发生交通事故吗?

答案

(1)0.9s(2)20m (3) 会发生交通事故

题目分析:(1)车速v1=40 km/h= m/s,由于在反应时间内汽车仍匀速行驶,根据车速v和反应距离s可计算驾驶员的反应时间Δt=.(3分)

(2)如果驾驶员的反应时间相同,由可计算出表格中A的数据为s3=10× m=20 m.(3分)

(3)车速v=72 km/h=20 m/s,   反应时间Δt=0.90 s+0.2 s=1.1 s(1分)

驾驶员的反应距离s=vΔt=20×1.1 m=22 m(1分)

刹车距离(2分)

停车距离L=s+x=54.3 m(1分)

由于停车距离L>50 m,故会发生交通事故.(1分)

点评:在追击相遇问题中,要明确速度相同是能否追上,相距最远或最近的临界条件,注意两个等量关系:时间和位移,本题更应该注意的是在反应时间内汽车做的是匀速运动

完形填空
阅读下面短文,根据所读内容在表格中的空白处填入恰当的单词。注意:每个空格只填一个单词。
You may admire both the romantic love story and the mysterious city of Rome in the movie Roman Holiday. If you are planning to visit Rome, here are some cultural dos and don’ts you should know.
Coffee Etiquette: Italian breakfast consists of pastry and a cup of Cappuccino or shot of espresso. Cappuccino is generally a morning drink and is not drunk after noon by real Italians. A post-dinner espresso, however, is a common practice.
Dinner Rules: Guests are expected to arrive for dinner reservations at least fifteen minutes late. In many restaurants, printed menus are for tourists. Regular patrons know to ask for the daily specials, which typically feature the freshest ingredients. Bread, is rarely together with butter or olive oil.
Drink the Water: Rome has plenty of public water fountains, and real Romans and their dogs always drink directly from them. Many people also refill their water bottle from these fountains.
Mind the Traffic: Unless there's a traffic light, or you are in a crosswalk, don't expect cars  to stop for you. Though crosswalks go first, in a car – crazy city, still you’d better keep cautious and walk cautiously.
Money: Always have some euros with you. Most major hotels, restaurants, and shops take credit cards, but many smaller operations either will either be unwilling to accept them for smaller purchases or do not accept credit cards at all. ATMs are available around the city and at the airports.
About Soccer: Most Italian men are passionate about their soccer. Arm yourself with some knowledge of Italy's soccer scene, and you will find ready conversation partners almost everywhere.
The Romans: The people here love to share their thoughts, opinions and emotions. They are creative, passionate, playful, occasionally rude or vain but always entertaining, and almost always good – humored.
Theme
Dos and Don’ts in Rome
Eating
▲Always have your breakfast with a cup of drink,
Cappuccino or espresso (76)          .
▲Arrive at least fifteen minutes last if you (77)         for dinner.
▲Bread, when served, is rarely (78)       by butter or olive oil.
▲(79)     some daily specials in restaurants directly, as regular customers do.
Drinking
▲Public water fountains are always (80)          by real Romans and their dogs.
▲Refill your water bottles from the fountains, too.
Traffic rules
▲Never expect cars to stop for you unless in a crosswalk or there is a traffic light.
▲When you are in a crosswalk, you’d better keep (81)      .
(82)         
▲Have some euros with you for smaller (83)         , because not all shops take credit cards.
Communicating
▲Start your (84)           with local people by talking about Italian soccer and they will be (85)       to share their opinions with you.
 
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