试题与答案

以35m/s的初速度竖直向上抛出一个小球,不计空气阻力,g取10m/s2.以下判

题型:选择题

题目:

以35m/s的初速度竖直向上抛出一个小球,不计空气阻力,g取10m/s2.以下判断错误的是(  )

A.小球到最大高度时的速度为0

B.小球到最大高度时的加速度为0

C.小球上升的最大高度为61.25 m

D.小球上升阶段所用的时间为3.5 s

答案:

A、小球做匀减速直线运动,当上升到最高点时,小球的速度减为零,再向下做匀加速直线运动,故A正确;

B、小球到达最高点时,小球仍受重力,故加速度仍为g;故B错误;

C、由v2=2gh可得,小球上升的最大高度h=

v2
2g
=61.25m,故C正确;

D、由v=gt可得,上升所用时间为t=

v
g
=3.5s,故D正确;

本题选错误的,故选B.

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题型:阅读理解

阅读理解。

     John H. Johnson was born in a black family in Arkansas City in 1918. His father died in an accident

when John was six. He was reaching high school age, but his hometown offered no high school for blacks.

     Fortunately (幸运地) he had a strong-willed, caring mother. John remembers that his mother told him

many times, "Son, you can be anything you really want to be if you just believe." She told him not to be

dependent on others, including his mother. "You have to earn success," said she. "All the people who work

hard don't succeed, but the only people who do succeed are those who work hard."

    These words came from a woman with less than a third-grade education.She worked hard as a cook for

two years to save enough money to take her son-then 15-to Chicago.

     Chicago in 1933 was not the promised land (乐土) that black southerners were looking for. John's

mother and stepfather could not find work. But here John could go to school, and here he learned the power

of words-as an editor (编辑) of the newspaper at Du Sable High School. His wish was to publish a magazine

for the blacks.

     While others discouraged him, John's mother offered him more words to live by: "Nothing beats a failure

but a try." She also let him pawn (典当) her furniture to get the $500 he needed to start the Negro magazine.

     It is natural the difficulties and failures followed John closely until he became very successful. He always

keeps his mother's words in mind: "Son, failure is not in your vocabulary." Now John H. Johnson is one of

the 400 richest people in America.

1. Why did John's mother decide to move to Chicago? Because           . [ ]

A. John's father died in his hometown when John was very young

B. life was too hard for them to stay on in their hometown, while life in Chicago would be better for them

    Negroes

C. there were no schools in their hometown

D. John needed more education and he could go to high school there

2. What's the best title of the passage? [ ]

A.How John H. Johnson became somebody

B.The mental (精神的) support from a great mother

C.The importance of a good education

D.The key to success for blacks

3. The underlined sentence in the fifth paragraph means           . [ ]

A. if you try, you will succeed in the end

B. a failure is difficult to beat, even if you try

C. a try is always followed by a failure

D. nothing but a try can help you out of failure

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