问题 选择题

“蹦极”是一项刺激的极限运动,一个重为F0的运动员将一端固定的长弹性绳绑在踝关节处,从高处跳下,测得弹性绳的弹力F的大小随时间t的变化图像如图所示。若将蹦极过程视为在竖直方向上的运动,且空气阻力不计,下列说法正确的是(    )

A.t1~t2时间内运动员处于超重状态

B.t3时刻运动员的速度最大

C.t1~t3时间内运动员受到的弹力冲量和重力冲量大小相等

D.t1~t5时间内运动员的机械能先减小后增大

答案

答案:D

题目分析:由弹性绳弹力F的大小随时间t的变化图象可知,0~t1时间内,运动员做自由落体运动,t1~t2时间内运动员做加速度逐渐减小的加速运动,处于失重状态,选项A错误;t2~t4时间内运动员的动能先减少后增大,机械能保持不变,选项B错误;t3时刻运动员的加速度方向向上,不为零,t4时刻运动员具有向上的最大速度,选项CD错误

点评:本题难度较小,明确图像中物体重力的大小,根据支持力与重力的关系进行判断,判断机械能的变化是根据除了重力做功以外其他力做功来判断的

阅读理解

阅读表达(共5小题;每小题2分,满分10分)

【1】The air was pleasant and the music was loud in the vast square in front of the New York State office building in Harlem(哈莱姆, 美国纽约市黑人居住区) as health advocates(支持者,提倡者) set up information tables for Harlem wellness Week. It was a wide-ranging effort to educate people about non-communicable diseases: Heart disease, cancer, lung disease, obesity, and so on.

【2】There is an economic effect caused by these diseases, especially in Harlem, one of the city’s poorest districts. Without healthy employees and healthy customers, you cannot have healthy business, says Patricia Ricketts of the Greater Harlem Chamber of Commerce, which sponsors Wellness Week.

【3】Dr. Jo Ivy Boufford is president of the New York Academy of Medicine, a Wellness Week partner. She says education about better nutrition is important, but that people with low incomes often lack the means to put what they know into practice. But there is hope. New York is very active in adovating good, effective public health policies. “New York City has banned smoking in public places, both indoors and outdoors. That is a fantastic example of what can be done, without having any impact on the economy. It is a city where you have bike paths. That is a good message for the world, because bikes make your transport active. That is good for your health and lowers air pollution,” she said.

【4】“It is not enough to focus on the management of disease through medication,” Dr. Boufford says. “That’s why health advocates will be trying to persuade UN officials during Wellness Week to pass resolutions that deal with road and transport design and construction and other potential causes of non-communicable diseases.”

小题1: What is the main idea of the text? (no more than 8words)

                                                                                 

小题2: Complete the following statement with words from Paragraph【4】.(no more than 3words)_______________ the management of disease through medication is not enough.

                                                                                 

小题3: What noninfectious diseases are mentioned in the text?( no more than 6 words)

                                                                              

小题4:Do you think it is necessary to hold a Wellness Week to prevent diseases? Why, or why not? (no more than 16 words)

                                                                                 

小题5: What does the word “That”(paragraph 3) refer to?(no more than 4 words)

                                                                            

单项选择题 案例分析题