问题
选择题
从离地H高处以速度V竖直向下抛出一个小球，若球撞地时无机械能损失，那么此球的回跳高度是
A．H+V2/2g
B．H-V2/2g
C．V2/2g
D．上述均有可能
答案
答案：A
题目分析：由竖直上抛运动和能量守恒定律可知上升的高度为H+V2/2g，故选A
点评：本题难度较小，上升到原来位置的速度大小依然是v
搜题请搜索小程序“爱下问搜题”
从离地H高处以速度V竖直向下抛出一个小球，若球撞地时无机械能损失，那么此球的回跳高度是
A．H+V2/2g
B．H-V2/2g
C．V2/2g
D．上述均有可能
答案：A
题目分析：由竖直上抛运动和能量守恒定律可知上升的高度为H+V2/2g，故选A
点评：本题难度较小，上升到原来位置的速度大小依然是v
| 选择方框中所给的句子，补全对话。 | |
| A: Hello, Daisy. B: Hi, Alice. I'm going to have a party next week. 1._____________ A: A party? That's cool! 2._____________ B: It's my birthday on Wednesday. I'm going to be sixteen. A: Oh, dear! I'm afraid I can't come on Wednesday. B: 3.____________ My birthday's on Wednesday, but the party's on Friday. A: Oh, that's OK. 4.____________ B: At 8:30. A: Right, that would be no problem. B: It's going to be at the London Hotel, near the town center on Shindy Street. A: OK. 5._____________ I've got a map. B: Wonderful. See you next time. A: See you. 1._____ 2._____ 3._____ 4._____ 5._____
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