问题 计算题

2007年4月18日零时起,全国铁路第六次大提速。《每日新报》报道:这些“比风还要快”的高速列车,都被冠以一个具有鲜明时代特征的名字:和谐号。 

(1)下表是“和谐号”列车的部分运行时刻表,请根据表中提供的信息,计算D609次列车从济南至四方全程的平均速度。

(2)全国铁路提速后,乱穿铁路面临的危险将增大。专家指出,时速达到200km/h时,500m以外的列车只需9s就能到达横穿铁路的行人面前。此外,时速200km/h的列车经过时,在铁路边掀起的风速将大于14m/s,铁路边的行人稍不留神就有可能被吸进轨道。请你分析说明行人为什么会被“吸”进轨道。

答案

解(1)D609次列车从济南至四试试看运行时间t=13h58min-11h28mi=2h30min=2.5h

D609次列车从济南至四方全程的平均速度

(2)高速运行的列车使铁路边的风速很大,因为气体流动速度越大压强越小,所以大气压把人压进轨道

单项选择题

Social-networking sites offer users easy ways to present idealized images of themselves, even if those ideals don’t always square with their real-world personalities. Psychology researcher Soraya Mehdizadeh has discovered a way to poke through the offline-online curtain: she has used Faeebook to predict a person’s level of narcissism and self-esteem.

Mehdizadeh, who conducted the study as an undergraduate at Toronto’s York University, gained access to the Faeebook accounts of 100 college students and measured activities like photo sharing, wall postings and status updates; she also studied how frequently users logged on and how often they remained online during each session. Her findings were published recently in Cyberpsyehology, Behavior and Social Networking.

After measuring each subject using the Narcissism Personality Inventory and Rosenberg Self-Esteem Scale, Mehdizadeh, who graduated from York this past spring, discovered narcissists and people with lower self-esteem were more likely to spend more than an hour a day on Facebook and were more prone to post self-promo-tional photos ( striking a pose or using Photoshop, for example). Narcissists were also more likely to showcase themselves through status updates (using phrases like "I’m so glamorous I bleed glitter") and wall activity (posting self-serving links like " My Celebrity Look-alikes" ).

Self-esteem and narcissism are often interrelated but don’t always go hand in hand. Some psychologists believe that narcissists--those who have a pervasive pattern of grandiosity, a need for admiration, as well as a lack of sympathy--unconsciously inflate their sense of self-importance as a defense against feeling inadequate. Not enough empirical research has been produced to confirm that link, although Mehdizadeh’s study seems to support it. Because narcissists have less capacity to sustain intimate or long-term relationships, Mehdizadeh thinks that they would be more drawn to the online world of virtual friends and emotionally detached communication.

Although it seems that Facebook can be used by narcissists to fuel their inflated egos, Mehdizadeh stops short of proclaiming that excessive time spent on Faeebook can turn regular users into narcissists. She also notes that social-networking sites might ultimately be found to have positive effects when used by people with low self-esteem or depression. "If individuals with lower self-esteem are more prone to using Facebook," she says, "the question becomes, ’ Can Facebook help raise self- esteem by allowing patients to talk to each other and help each other in a socially interactive environment’ I don’t think it’s necessarily a bad thing that people with low self-esteem use Facebook.

Narcissists may()

A. be online for a long time

B. only upload the photos of their own

C. own the p sympathy

D. be self-serving

问答题