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问题 选择题

对做单向减速运动的物体，下列说法中正确的是（ ）

A．速度和位移都随时间减小

B．速度和位移都随时间增大

C．速度随时间增大，位移随时间减小

D．速度随时间减小，位移随时间增大

答案

D

题目分析：做减速运动，则物体的速度随时间在减小，物体做单向运动，所以物体的位移随时间的变化在增大，故D正确，

点评：此类型的题目是运动学中一道基础性的题目，非常简单，

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改写后的课文内容填空 （共10个空，每空1分，满分10分）

Frederick William I, to whom the Amber Room b________小题1:, could not have imagined it would have such an a________小题2:story. The Amber Room was designed in the fancy style popular in those days, d________小题3: with gold and jewels. He, however, gave it to Peter the Great as a g________小题4:. For the Czar, the Amber Room served as a small r________小题5: hall for important visitors. Later, Catherine II told her artists to add more d________小题6:to the Amber Room to make it even more beautiful.

During World War II, the Nazi army attacked St Petersburg. Though the Russians were able to remove some f________小题7:and small art objects, some of the Nazis s________小题8: stole the Amber Room itself. There is no d________小题9: that the Amber Room was put on a train for Königsberg. What happened to it later r________小题10: a mystery.

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问答题

如图，一物块以150J的初动能从斜面底端A沿斜面向上滑动，到B时动能减少90J，机械能减少30J．

求：（1）第一次到达最高点时的重力势能为多少？（取斜面底端为零势点）

（2）若回到A时和挡板相碰无能量损失，物块运动过程中通过的总路程为多少？（设物块质量为1kg，斜面倾角为30°，g=10m/s2）
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