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问题 解答题

将下列各数按从小到大的顺序排列．

100，7，100.071，100.69，100.701

______．

答案

依据小数大小的比较方法可知：

100.071＜100.69＜100.7＜100.701；

故答案为：100.071＜100.69＜100.7＜100.701．

问答题

如图所示，木块质量m=1.04kg，在与水平方向成θ=37°角、斜向右上方的恒定拉力F作用下，以a=2.0m/s2的加速度从静止开始做匀加速直线运动，在3s末时撤去拉力F．已知木块与地面间的动摩擦因数μ=0.4，取重力加速度g=10m/s2，sin37°=0.6，cos37°=0.8．求：

（1）拉力F的大小

（2）物体在5s内滑行的总位移．
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问答题

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48) Man found that his own muscles were too weak for the work which he wanted to do; he explored many other forms of power until now he has his hands on the ultimate source of physical energy, the nuclear power. From man’s earliest days the flight of birds has raised his wonder and desire. Why should he not fly as they did Then he began to experiment. At last he learnt how to make the right machines to carry him through the air. Now he can fly faster than sound. Already he has plans for conquering space, and a series of experiments has been completed. 49) It will not be long now before man takes a giant step away from his planet and visits the moon, learning what it is like to have no weight to his body, no upward direction and no downward.
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