问题 问答题

(1)经多长时间两球发生第一次碰撞?碰撞前小球A的速度为多大?

(2)在以后的各次碰撞中,相邻两次碰撞间隔的时间是否相等(如相等,为多少;如不等,说理由)?

(3)从加上电场起计时,经多长时间小球A以多大的速度与小球B发生第3次碰撞?

答案

(1),

(2)

(3)

(1)小球A从开始运动至与B球碰前有:

               

由上三式可得:,(每式1分,共5分)

(2)在每次碰撞过程中有:

由上可得:,,

即每次碰后A、B两球交换速度,绘出它们的图象如下

可见:以后的相邻两次碰撞间隔的时间相等,为

(3)由图可直接得到:从加上电场起计时,经时间

小球A与小球B发生第三次碰撞,此时球A速度为

阅读理解
阅读下面短文,掌握其大意,然后从各题所给的四个选项(A、B、C和D)中,选出最佳选项。
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