问题 实验题

某同学设计了一个用打点计时器探索碰撞中不变量的实验:在小车A的前端装有橡皮泥,推动小车A使之匀速运动,然后与原来静止在前方的小车B相碰并粘合成一体,继续做匀速运动,他设计的装置如图所示,在小车A的后面连着纸带,电磁打点计时器电源频率为50 Hz,长木板的一端下垫着小木片用以平衡摩擦力。

(1)若已得到打点纸带如图所示,并测得各计数点间距标在下图上,A为运动起始的第一个点,则应选________段来计算A碰前速度,应选________段来计算A和B碰后的共同速度。

(2)已测得小车A质量为m1=0.40 kg,小车B的质量为m2=0.20 kg,由以上测量可得:

碰前两车质量与速度乘积之和=________kg·m/s;

碰后两车质量与速度乘积之和=________kg·m/s。

(3)结论____________________________________________。

答案

(1)BC,DE

(2)0.420,0.417

(3)在误差允许的范围内,碰前的质量与速度乘积之和等于碰后的质量与速度乘积之和,即碰撞过程中的不变量为质量与速度乘积之和

单项选择题

The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question. Answer all questions following the passage on the basis of what is stated or implied in the passage.

James Joyce revolutionized the novel, the short story, and modern literature as we know it. He was born in Dublin, the first of 10 children in a Catholic family. His father was a civil servant whose poor financial judgment left the family impoverished for much of Joyce’s youth. Young James attended Dublin’s fine Jesuit schools, which gave him a firm grounding in theology and classical languages--subjects that appeared repeatedly in his later work. The story of his early life and his intellectual rebellion against Catholicism and Irish nationalism are told in the largely autobiographical novel A Portrait of the Artist as a Young Man.

In 1902, at the age of 20, Joyce left Dublin to spend the rest of his life in Paris, Trieste, Rome, and Zurich, with only occasional visits back home. Despite this self-imposed exile, Dublin was the setting for most of his writings. Dubliners (1914), Joyce’s most accessible work, is a collection of short stories describing the paralyzing social mores of middle-class Catholic life. "The Dead," the final story in the collection, is frequently listed as one of the finest short stories ever written.

Joyce’s next book, Ulysses, took seven years to write; once he finished writing it, he almost couldn’t find anyone to publish it. Upon the novel’s publication, both Ireland and the United States immediately banned it as obscene. Despite these obstacles, Ulysses has come to be generally recognized as the greatest twentieth-century novel written in English. The novel was revolutionary in many ways. The structure was unique: Joyce recreated one rill day in the life of his protagonist, Leopold Bloom, and modeled the actions of the story on those of Ulysses in the Odyssey. In recounting Bloom’s day, Joyce mentions everything that happens to Bloom--including thoughts, bodily functions, and sexual acts--providing a level of physical actuality that had never before been achieved in literature. To provide a psychological insight comparable to the physical detail, Joyce employed a then-revolutionary technique called stream of consciousness, in which the protagonist’s thoughts are laid bare to the reader.

From 1922 until 1939, joyce worked on a vast, experimental novel that eventually became known as Finnegan’s Wake. The novel, which recounts "the history of the world" through a family’s dreams, employs its own "night language" of puns, foreign words, and literary allusions. It has no clear chronology or plot, and it begins and ends on incomplete sentences that flow into each other. Many of Joyce’s supporters thought he was wasting his time on the project, although the playwright Samuel Beckett, who later won the Nobel Prize for Literature, helped Joyce compile the final text when his eyesight was failing. Today, Finnegan’s Wake is viewed as Joyce’s most obscure and possibly most

The author most likely mentions James Joyce’s childhood, family, and education to serve what purpose ?()

A. To suggest that he had to write in order to make a living

B. To suggest that he became a writer because of his father’s influence

C. To provide the background and cultural context for his literary work

D. To provide evidence that his literary genius was present when he was a child

E. To explain his opposition to Catholicism and socialism in his later life

多项选择题