问题
计算题
在排球比赛中，运动员在离地3m处击中排球，使排球以15m/s的速度水平飞出，若不计空气阻力，g取l0m/s2。求：
（1）排球落地点与击球点之间的水平距离；
（2）离落地点为2m处的另一个运动员至少用多大的速度跑动，才能在球落地前接到球？
答案
（1）3
m
（2）
m/s
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在排球比赛中，运动员在离地3m处击中排球，使排球以15m/s的速度水平飞出，若不计空气阻力，g取l0m/s2。求：
（1）排球落地点与击球点之间的水平距离；
（2）离落地点为2m处的另一个运动员至少用多大的速度跑动，才能在球落地前接到球？
（1）3m
（2）m/s
Ali is from a Middle Eastern country. He now stays in the USA. He smokes a lot of cigarettes every day. He has smoked for nine years. Ali says, “I tried to quit smoking in my hometown, but it was impossible. My parents smoke. My brothers smoke. All my friends smoke. At parties and at meetings, almost all the men smoke. Here in the United States, not as many people smoke. 小题1: ” Many smokers are like Ali: they want to stop smoking. 小题2: They know it can cause cancer and heart disease. But it is difficult for them to give up smoking because cigarettes have a drug in them. The drug is nicotine. People who smoke a lot need nicotine. 小题3: The nicotine makes him sick. In a few days, the smoker's body is used to the nicotine, and he feels fine. Later, the smoker needs nicotine to keep feeling fine. Without nicotine, he feels bad. 小题4: Many people who quit will soon smoke again. At a party or at work they will decide to smoke "just one" cigarette. Then they will smoke another cigarette, and another. Soon they become smokers again. 小题5:
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