问题 选择题

质量分别为的两个物体甲和乙放在表面光滑且足够长的木板上,随木板一起以水平向右的相同速度沿同一直线做匀速直线运动,当木板突然停止时,以下说法正确的是:

A若,甲将和乙发生碰撞

B 若,甲将和乙发生碰撞

C 若,甲将和乙发生碰撞

D 无论两个物体质量关系如何,都不会碰撞

答案

答案:D

木板停止前,甲、乙物块和木板一起作匀速直线运动,并且两物块和木板具有共同的速度,当木板突然停止时,由于物块在光滑接触面上,因此两物块球由于惯性,还要保持原来大小不变的速度做匀速直线运动,因此两个小球间的距离不变,一定不会相碰.

故选 D.

点评:一切物体都有惯性;此题主要考查学生对惯性的理解和应用,会用惯性知识分析物体的运动状态.

写作题

书面表达。

     Jess really felt very happy. When he arrived at his seat in the classroom that morning, he found an

invitation on his desk. It was from several of his classmates asking him to join them on a camping trip.

This was the first time he was asked to join in an out-of school activity. Why were they asking him now?

Nobody seemed to like him. In fact, he had been so lonely that he drowned his feeling with food. As a result,

he hat put on a lot of weight, and this gave the kids something more to make fun of him.   

      Cindy, who was standing near Jess when he read the invitation, went out quickly to tell the others that

the trick had worked. Everyone was pleased that Jess thought that was true. But there was no camping trip.

Tile whole thing was made up.   

      At first, Cindy thought it was fun. But later, when Jess told her that he was going to buy a sleeping bag

with his savings, Cindy bad second thoughts. She knew that Jess's family had little money, and she hated to

see him spend his savings on something he would never use. Cindy also hated to tell Jess the truth. Her close

friends would be angry with her.   

      

     What could Cindy do? Please write a letter to help her.

     请你帮Cindy 想一个办法解决问题, 并写信告诉Cindy 你认为最佳的解决方案。

     信中请写清Cindy 面临的问题是什么;阐明你的态度和解决方法;并请注意信的格式。

     字数不得少于100字。

     _______________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

问答题 论述题