题干

某同学利用图甲所示装置做“研究平抛运动”的实验,根据实验结果在坐标纸上描出了小球水平抛出后的运动轨迹,但不慎将画有轨迹图线的坐标纸丢失了一部分,剩余部分如图乙所示.图乙中水平方向与竖直方向每小格的长度均代表0.10m,P1,P2和P3是轨迹图线上的3个点,P1和P2、P2和P3之间的水平距离相等.完成下列填空:(重力加速度取9.8m/s2

若已测知抛出后小球在水平方向做匀速运动,则小球从P1运动到P2所用的时间为____ s,小球抛出后的水平速度为____ m/s (结果取两位有效数字).

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0.20,3.0

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    In 1863, the great novelist Jules Verne wrote a novel called Paris in the Twentieth Century. In the book he used the full power of his great ability to forecast the coming century. Unfortunately, the manuscript (手稿) was lost until his great-grandson happened to discover it lying in a safe where it had been carefully locked away for almost 130 years. Realizing what a treasure he had found, he arranged to have it published in 1994, and it became a bestseller at once.

    Back in 1863, kings still ruled the ancient world in Europe, with so many poor people working in the fields. And steam power was just beginning to change the world. But Verne predicted that Paris in 1960 would have glass skyscrapers, air conditioning, TV, high-speed trains, gas-powered vehicles, and even something similar to the Internet. Verne described life in modem Paris almost without any mistakes.

    Just two years later Verne made another amazing prediction. He wrote From the Earth to the Moon, in which he predicted the details of the task that sent several astronauts to the moon 100 years later in 1969. He correctly predicted the size of the space capsule, the number of astronauts who would carry out the task, the weightlessness that the astronauts would experience, and the final landing in the ocean.

    How was Jules Verne able to predict 100 years into the future successfully? Although he was not a scientist himself, Verne often turned to scientists, asking them questions about their opinions of the future. He collected a vast amount of information about the great scientific discoveries of his time. Verne realized that science would make it possible for many amazing things to appear in the future. The secret of his successful prediction was his belief in the power of science to change society.