题目

a subway train starting from rest along a straight track has a uniform acceleration of 1.8m/s2 for the first 20m it travels.
a.calculate its speed when it has traveled 10m.
b.When it has traveled 20m,will its speed be less than double,double,or more than double its speed at 10m?
c.Now calculate its speed when it has traveled 20m .Does this agree with you answer B

提问时间：2020-07-25

答案

题目说的是火车从静止开始 做加速度1.8m/s^2的直线运动.1.计算10m时的速度2.当运行了20m,火车的速度和10m的2被什么关系、大于?小于?3.计算20m的速度,是否和你在2中选择的一样.S=Vt^2/2a10m时候的速度Vt=6m/s20m时候...