问题 计算题

[物理——选修3-5](15分)

(1)(5分)下列说法正确的是                                                                             (  )

A.放射性元素的半衰期随温度的升高而减小

B.放射性元素放射出的射线、射线和射线,电离能力最强的是射线

C.衰变成要经过6次衰变和4次衰变

D.原子从较高的激发态向较低的激发态或基态跃迁的过程,是吸收能量的过程。E.光电效应的实验结论是:对于某种金属,超过极限频率的入射光频率越高,所产生的光电子的最大初动能就越大

(2)(10分)如图所示,在高为h=5m的平台右边缘上,放着一个质量M=3kg的铁块,现有一质量为m=1kg的钢球以v0=10m/s的水平速度与铁块在极短的时间内发生正碰被反弹,落地点距离平台右边缘的水平距离为l=2m.已知铁块与平台之间的动摩擦因数为0.5,求铁块在平台上滑行的距离s(不计空气阻力,铁块和钢球都看成质点).

答案

(1)C E

(2)1.6m

(1)C E (5分)

(2)(10分)设钢球反弹后的速度大小为v1,铁块的速度大小为v,碰撞时间极短系统动量

     ①

钢球做平抛运动

              ②

           ③

由②③①解得t=1s,v1=2m/s,v=4m/s

铁块做匀减速直线运动,加速度大小

=5m/s2  ④

最终速度为0,则其运行时间  =0.8s       ⑤

所以铁块在平台右滑行的距离  =1.6m         ⑥

评分标准:本题10分,①⑥各3分, ②③④⑤各1分.

阅读理解

When John Weston awoke that morning, he remembered that his mother was going into hospital. He hadn’t worked out quite what was wrong with her. He knew, though that she hadn’t been well for some time now, and it had become almost familiar to him to see her eyes narrowed in a sudden attack of pain, and her hand pressing against her heart. Their own doctor, who she had finally gone to for advice, had sent her to an expert who knew all about these things. He had told her that just as soon as there was a bed for her, she would have to come into his hospital where he could look after her himself.

During the weeks since then the pains had come even more frequently, and the narrowed eyes became an almost permanent part of her expression. Always rather sharp, she began losing her temper over little things so that John’s father kept his thoughts to himself more and more. John, as ready as possible to make allowances, tried to think what it would be like to have toothache all the time and how bad-tempered that would make you.

So his mother would go into hospital for a few days. He was going to stay with his Aunt Daisy till she came back, and his father would stay on at home by himself. John’s cousin, Mona, was to come in and make the bed and wash the pots and dust round now and again. That was the arrangement, and John didn’t care much for it. Apart from missing his mother(and he was glad she was going away because they would make her better), he wasn’t very fond of his Aunt Daisy because she was even more bad-tempered than his mother.

小题1:Mrs Weston went to see her doctor_________.

A.as soon as she realized that something was wrong

B.only after her husband advised her to

C.a long time after the trouble began

D.when John asked what was wrong with her小题2:what did Mrs Weston’s own doctor decide to do?

A.he decided to send her to hospital

B.he decided to get an expert to examine her

C.He decided to treat her himself

D.He advised her to wait for a few weeks.小题3:how did John react to his mother’s bad temper?

A.he tried to imagine himself in her place.

B.He tried not to notice it.

C.He pretended that he had toothache.

D.He behaved himself as well as possible.小题4:John regarded ______as most bad-tempered.

A.his father

B.his mother

C.his cousin Mona

D.his aunt Daisy

单项选择题