一根细长绳的下端系一金属小球，上端固定，制成一个摆，把小球拉离竖直位置松手，让他摆动起来，如图所示，可以观察到小球摆动过程中摆动的幅度会逐渐减小，最终停下来，对于小球在摆动过程中的能量转化情况，下列说法不正确的是
A．小球从高处向低处摆动过程中，势能部分转化为动能
B．小球从低处向高处摆动过程中，动能部分转化为势能
C．小球摆动过程中机械能守恒
D．小球依次经过最低点时，动能会逐渐减少
答案：C
由于小球摆动过程中摆动的幅度会逐渐减小，最终停下来，说明小球摆动的过程中机械能不守恒，小球的机械能逐渐转化成了内能；故C是不对的。
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| When I was a boy, every holiday that I had seemed wonderful. My 1 took me by train or by car to a hotel by the 2 . All day, I seem to remember, I 3 on the sands with strange 4 children. We made houses and gardens, and 5 the tide destroy them. When the tide went out, we 6 over the rocks and looked down at the fish in the rock-pools. In those days the 7 seemed to shine always brightly 8 the water was always warm. Sometimes we 9 beach and walked in the country, exploring (搜寻) ruined houses and dark woods and climbing trees. There were 10 in one's pockets or good places where one could 11 ice creams. Each day seemed a life-time. Although I am now thirty-five years old, my idea of a good 12 is much the same as it was. I 13 like the sun and warm sand and the sound of 14 beating the rocks. I no longer wish to 15 any sand house or sand garden, and I dislike sweets. 16 , I love the sea and often feel sand running through my fingers. Sometimes I 18 what my ideal (理想的) holiday will be like when I am 19 . All I want to do then, perhaps, will be to lie in bed, reading books about 54 who make houses and gardens with sands, who watch the incoming tide, who make themselves 20 on too many ices creams. | ||||
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