题目

听下面一段较长对话，回答以下小题。【1】Why is the man so sad?A.His walk was ruined.B.His dog had an accident.C.He can’t compete in the show.【2】What do the speakers probably enjoy doing?A.Showing dogs.B.Running after cars.C.Playing baseball with his friends.【3】Why does the man want tea?A.He feels cold. B.He is quite thirsty. C.He wants to calm himself down. 答案：【答案】【1】B【2】A【3】C【解析】【原文】M: Oh my god. I can’t believe that this happened. This is horrible.W: What? What happened?M: Well, this morning I took Lily out for a walk like I always do. We were practicing trick for the up-coming show. I threw the ball harder than I usually do and it bounced into the street. I tried to stop her but she just kept on running and … a如图所示，在动摩擦因数μ=0.2的水平面AB上，水平恒力F (F大小未知)推动质量为m=1kg的物体从A点由静止开始作匀加速直线运动，物体到达B点时撤去F，接着又冲上光滑斜面（设经过B点前后速度大小不变），最高能到达C点。用速度传感器测量物体的瞬时速度，并在表格中记录了部分测量数据（g取10m/s2）。t/s0.00.20.4…2.22.42.6…v/(m/s)0.00.40.8…3.02.01.0… 【小题1】求出物体到达B点时的速度和时间；【小题2】若撤去推力F，在A处给物体一个水平向左的初速度v0，恰能使物体运动到C点，求此初速度v0的大小。