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如图所示,长为1.8m的轻绳,上端悬挂在离地面3.6m高的天花板上,下端系一个质量为2kg的小球.现将球拉到天花板上,放手后球自由下落,在轻绳绷紧时,绳断球落地,从放手到球落地整个时间为1.2s.若小球与绳作用时间及绳的伸长均可忽略不计,求:

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    White-collar workers increasingly unhealthy

    An increasing number of white-collar workers in Shanghai are getting failing grades on their physical examinations, according to a white paper on the health of white-collar workers in Shanghai.

    Carried out by Shanghai Foreign Service Group,a human resources company,the report indicated that more than 53 percent of males are overweight,46 percent suffer from a fatty live and about 26 percent have elevated blood lipids(血脂).However,females are more often diagnosed as having breast lesions(乳房病变)that could lead to cancer (85 percent),thyroid(甲状腺)disorder (34 percent) and hemorrhoids(痔疮)(23 percent).

    Though the report also found that white-collar workers were paying increasing attention to their health—with about 84 percent saying they followed their condition closely or very closely—those with healthy lifestyles dropped to 64 percent last year from 77 percent in 2015.

    The report came from about 500,000 physical exams taken by while-collar workers in Shanghai over the past five years.“I always eat and drink too much and never exercise,”said Wei Ruoxi,a 26-year-old working in finance who is struggling with being overweight.“I know what a healthy lifestyle looks like,but the job just brings too much pressure and squeezes out exercise time,”she added.Hu Xiaolong,30,an accountant in Shanghai,said he was determined to live healthily from now on.“My recent physical examination shows a little shadow in the lung,which startled me when I heard it.I really need to quit these habits like smoking and staying up late.”

    The white paper also showed that more people are turning to commercial health insurance to cope with financial risks caused by health problems.The popularity of insurance purchases among the participants reached 15.3 percent last year,a rise of 4 percentage points in just one year.Most participants also expected their companies to help them with effective health management,such as offering membership cards for gyms,flexible working schedules and regular physical examinations.