题干

游泳时,有的人会有这样的体验:当人站立在水中且身体要浸没时,池底对脚的支持力几乎为零.假如一位重500N的同学正在体验这种感觉,此时他受到的浮力方向为____,大小约为____ N,排开水的体积约为____ m3 (g=10N/kg,水的密度1.0×103kg/m3).

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竖直向上,500,5×102

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    Jeanne Calment, a French woman, became a record breaker on 17 October of 1995, when at the age of 120 years and 238 days, she became the longest-lived human being on record. A Japanese man died in 1986 at the age of 120 years and 237 days.

    Jeanne Calment lives in a small old people's home in the south of France; her husband, her only child and her grandson have all died. She is nearly blind and deaf and is always in a wheelchair, but her doctor describes her as being more like a 90-year-old in good health than someone of 120. She still has a lively sense of humor. When asked on her 120th birthday what she expected of the future, she replied: A very short one. She also remarked that she thought the good Lord had forgotten all about her.

    So what is the key to a long life? According to some doctors, diet, exercise and no smoking are the three important factors. Jeanne Calment has followed two of the tips. She has always eaten a healthy diet, and she used to do exercise every day until she broke her leg at the age of 115. However, until recently she drank two glasses of strong red wine a day, and she does smoke (now only a little). Besides, Jeanne Calment might have got very good genes from her parents. Her father lived to the age of 94 and her mother to 86.

    A local lawyer bought her house when she was 80 under an agreement that he would pay her some money every year until her death. It must have seemed a good move at the time, but so far the lawyer has paid her at least three times the value of the house. Every year on her birthday Jeanne Calment sends him a card saying: Sorry, I'm still alive!