搜题请搜索小程序“爱下问搜题”
问题 实验题

如图为“碰撞中的动量守恒”实验装置示意图

（1）入射小球1与被碰小球2直径相同，它们的质量相比较，应是m1____m2.

（2）在做此实验时,若某次实验得出小球的落点情况如图所示.假设碰撞中动量守恒,则入射小球质量m1和被碰小球质量m2之比m1:m2=           .

答案

>  　　　　　　  4：1

选择题

The poem _____ in 1881 described a moving story that happened on Christmas Eve. [ ]

A. written

B. being written

C. was written

D. to be written

查看答案
选择题

A digital ring is locked on every newborn baby’s foot _______ they are taken by strangers out of the hospital.

A．because

B．when

C．so that

D．in case
查看答案