问题 填空题

如图所示的实验装置可以验证牛顿第二定律,小车上固定盒子,盒子内一个盛有沙子.

(1)验证在质量不变的情况下,加速度与合外力成正比

从盒子中取出一些沙子,装入沙桶中,称量并记录沙桶的总重力mg,将该力视为合外力F,对应的加速度a则从打下的纸带中计算得出.多次改变合外力F的大小,每次都会得到一个相应的加速度.本次实验中,桶内的沙子取自小车中.故系统的总质量不变.以合外力F为横轴,以加速度a为纵轴,画出a-F图象,图象是一条过原点的直线.

①a-F图象斜率的物理意义是______

②你认为把沙桶的总重力,增当作合外力F是否合理?答:______(填“合理”或“不合理”)

③本次实验中,是否应该满足悬挂的沙桶总质量一定要远远小于小车(包括盛沙的盒及盒 内的砂)的总质量?答:______(填“是”或“否”);理由是______.

(2)验证在合外力不变的情况下,加速度与质量成反比

保持桶内沙子质量不变,在盒子内添加或去掉一些沙子,验证加速度与质量的关系.本次实验中,桶内的沙子总质量不变,故系统的所受的合外力不变.用图象法处理数据时,以加速度a为纵轴,应该以哪一个质量的倒数为横轴?

A.小车质量、盒子及盒内沙子质量之和

B.小车质量、盒子及盒内沙子与悬挂的沙桶(包括桶与桶内的沙)质量之和

答:______(填“A”或“B”)

答案

(1)①将车内的沙子转移到桶中,就保证了M+m不变,即系统的总质量不变,研究对象是整个系统,a=

F
M+m
=
mg
m+M

可见a-F图象斜率的物理意义是

1
M+m
,即系统的总质量倒数(小车、盒子及盒内沙子、悬挂的桶以及桶内沙子质量之和倒数)

②把沙桶的总重力,当作合外力F是合理的.

③因为实验的研究对象是整个系统,系统受到的合外力就等于mg,所以不需要满足满足悬挂的沙桶总质量一定要远远小于小车(包括盛沙的盒及盒 内的砂)的总质量.

(2)向小车内添加或去掉部分沙子,是改变系统的总质量M+m,而系统的合外力仍等于所悬挂沙桶的重力mg,保证了合外力不变.所以用图象法处理数据时,以加速度a为纵轴,应该以M+m倒数为横轴,即小车质量、盒子及盒内沙子与悬挂的沙桶(包括桶与桶内的沙)质量之和.故选B.

故本题答案为:(1)①系统的总质量倒数(小车、盒子及盒内沙子、悬挂的桶以及桶内沙子质量之和倒数),②合理

③否,因为实验的研究对象是整个系统,系统受到的合外力就等于mg

(2)B

选择题
阅读理解

Women who want to succeed at work should resist the temptation to act like men, scientists have said. Studies show that ambitious women are often less likely to get ahead than those who show more female characteristics. However, if they try to adapt, promotion comes their way. The findings, which will let assertive (过分自信的) women down, suggest that the best way for a woman to succeed in a man’s world is to act like a lady.

Past research has shown that women with self-confidence and other characteristics linked with successful management can be put aside at work in favor of gentle types. It is thought that while such characteristics are highly praised in men, ambitious women are penalized for not being feminine enough. Instead of being seen as strong managers, ambitious women are in an unfavorable situation.

In one US study, researchers explored personal details from university students applying for a summer job at a bank. A women applicant who attempted to apply for special wages to pay her transport or living costs was three and a half times less likely to get a job offer than a similar male. In fact, this kind of woman was the least likely to get taken on.

The latest study set out to explore what women who are naturally assertive could do to get ahead in the workplace. Eighty young men and women completed surveys about their personality while studying in college. Around eight years later, the researchers got back in touch with them to find out how their careers were going. Some had been promoted five times, others just once or twice. The results showed that ambitious women who stick to their decisions had been promoted less than more feminine groups. But the ambitious women who made a conscious effort to not appear to be threatening by “self-controlling” their behavior had done better than those who had carried on ignoring others’ views.

小题1: What does the underlined word “penalized” mean in the second paragraph?

A.Treated badly

B.Asked to leave

C.Looked down upon

D.Made sb. have a disadvantage小题2:According to the passage, if an ambitious woman and a similar man both ask the company for an extra payment, ______.

A.the woman is less likely to be accepted

B.the woman will work harder if she gets the payment

C.the man can make a good impression on the boss

D.they can be both accepted if they use proper words小题3:The ambitious women in the latest study ______.

A.had been promoted only once or twice

B.tried hard to be as successful as gentle types

C.were more accepted at work after they controlled their behavior

D.filled in the surveys after they graduated from college小题4:What can we learn from the passage?

A.Successful management is highly praised in women.

B.Some women will be disappointed by the massage.

C.Men acting like a lady are likely to be promoted at work.

D.The latest study was aimed at how to become a successful boss.小题5:What’s the main idea of the passage?

A.How assertive women can control their behavior.

B.Feminists can do better by controlling their behavior.

C.Acting like a man won’t get women promoted at work.

D.How the ambitious women can avoid acting like men.