题目

在做《研究匀变速直线运动》的实验时，某同学得到一条纸带，如图7所示，并且每隔四个计时点取一个计数点，已知每两个计数点间的距离为s，且s1＝0.96cm，s2＝2.88cm，s3＝4.80cm，s4＝6.72cm，s5＝8.64cm，s6＝10.56cm，电磁打点计时器的电源频率为50Hz。计算此纸带的加速度大小a＝___________m/s2，打第4个计数点时纸带的速度大小v＝_________________m/s。请你依据本实验推断第6记数点和第7记数点之间的距离是___________ cm。Last Wednesday,when school children were travelling home by bus from Yucai Middle School,a car hit their bus.Luckily,no one was hurt.The accident happened because the driver of a red car,Mr.Zhang,68,became ill and fell down on the steering(方向盘)while driving.His car then hit a white car.And the white car hit the school bus.Luckily,nobody was driving fast. 1.The driver of the bus,Mr.Li,stopped the bus at once. 2.And then he got out to see if he could help anyone.Mr.Wang,the driver of the white car,was not hurt and was trying to push his car to the side of the road.No cars could pass because of the accident. 3.Mr,Li tried to help Mr.Zhang. 4.So Mr.Li called an ambulance(救护车). 5.It was difficult for the ambulance to reach there.With the help of the police,the traffic could move again.Soon the ambulance(救护车) took Mr.Zhang to the hospital.A. Mr.Zhang didn’t answer when Mr.Li asked him if he was all right.B. No one was hurt.C. But the accident caused a large traffic jam堵塞.D. And some other drivers got out of their cars to help Mr.Wang.E. He asked the children not to leave the bus.