站在百米赛跑终点的计时员，在听到发令员的枪声后才按表计时，测得运动员的成绩为13.69s，求运动员的真实成绩是多少？（设当时气温为15℃，无风）
解：声音的传播需要时间，声音传到终点时运动员已经开始跑了，
s=100m，V=340m/s，
t=
=
≈0.29s；
所以真实成绩是计时时间加上声音100米传播的时间，
即：13.69s+0.29s=13.98s
阅读下面对话，从方框内7个选项中选择5个恰当Li Meng is studying in a middle
B: Not yet. 小题1: A: I’m going to the bookstore. Would you like to go with me? B: Sure. 小题2: A: Well, I want to buy some story books. B: That’s great. What kind of stories do you like? A: 小题3: What about you?B: Me, too. My favorite book is The Old Man and the Sea. A: I know that book. 小题4: B: You are right. Have you read any books by young writers born in the 1980s? A: Of course, and I like reading their works on the Internet. B: Haha! 小题5: A: That’s right. |