甲、乙、丙三物体同时同地出发做直线运动，运动情况如图所示。
（1）试分析在20 s时间内三个物体的运动情况。
（2）甲物体运动的路程是多少？
（3）丙物体的平均速度大小是多少？
解：（1）由题意知三物体均做直线运动，区别在于：乙做匀速直线运动，甲做速度先减小后增大的往返的直线运动，丙做速度不断增大的单向直线运动
（2）甲物体先向位移正方向运动，通过的路程为100m，后向位移负方向运动，运动路程20m，所以甲总路程为120m
（2）丙物体的平均速度：
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| Zheng Tao is five years 1 . He is a lovely boy. He plays 2 other children in the small park each day. The park is near his building. His mother buys new clothes for 3 . The clothes are expensive and nice. Zheng Tao feels very happy. "Mum, can I go out and play with my friends? I want them to 4 my new clothes," asks Zheng Tao. "Yes, please keep your clothes 5 "says the mother. She's going to do some cooking. "We'll 6 supper after your comes back. " 7 about six his father comes back from work. Zheng Tao goes home for supper. "Why do you have so much earth on your clothes? 8 his mother. "You shouldn't 9 the nice clothes dirty." says the mother. "I'm sorry, Mum." says Zheng Tao,"I have 10 time to take off my clothes when I fall." |
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