问题 选择题

如图所示,从倾角为θ的斜面上的M点水平抛出一个小球. 小球的初速度为,最后小球落在斜面上的N点,且重力加速度为g, 由上述条件某同学试图求出:①小球什么时刻与斜面间的距离最大;②小球空中运动的时间;③M、N之间的距离;④小球落到N点时的速度大小和方向等4个量。那么你认为他最多可以求出其中的(   )

A.1个

B.2个

C.3个

D.4个

答案

答案:D

题目分析:由题意可知,将初速度沿斜面和垂直于斜面进行分解,同时将加速度也同方向分解,当垂直于斜面的速度为零时,小球距离斜面最远,由于初速度和加速度已知,所以与斜面间距离最大的时间可求;小球飞过的位移与水平方向成θ角;将位移分别沿水平方向和竖直方向分解,由几何关系可知:解得:,故平抛运动的时间可求;由时间可求得小球经过的竖直高度和水平位移;则由几何关系可知M、N之间的距离;由vy=gt,可求得竖直分速度,由速度的合成与分解可求得最后末速度的大小和方向。故选D.

完形填空

Sumo wrestlers (相扑选手) are usually big, heavy men. The biggest sumo wrestler of all the time is Koni-shiki, who now  16   about 230 kg. Born in Hawaii, he was   17   a big boy. When he was a teenager, some people  18   he go to Japan and become a sumo wrestler.

Although he took their advice, at first it was a  19  life. “I had to clean the toilets and   20   the rubbish (垃圾),” Konishiki remembered, “I knew I had to  21   to life in Japan. I said to myself, ‘I  22   learn Japanese.’ Soon I could  23   it quite well.”

Konishiki’s career started  24  , and he was soon upgraded to a higher rank. But despite his  25   he soon had health problems. The doctors told him that he should  26  some weight. “I started dieting. I  27   to do it. But I did it too  28  ,” he said, “I lost some of my strength, too.”

He lost a lot of fights, and then his parents got  29  in a car crash. “I must go and  30    them,” he thought. Though it was only three days  31   a big tournament (锦标赛), he flew back to Hawaii. Despite his  32  , they were not badly injured.

When he returned, he knew that he had to do well. The newspapers said, “Konishiki must win,   33  he will go down in rank.”

Though he had many problems, Konishiki won 14 of his 15 fights, and won the Emperor’s Cup. He was so  34   that he cried. “You ought not to show your feelings,” he said, “but I couldn’t  35   it.”

小题1:

A.means

B.measures

C.weighs

D.has小题2:

A.always

B.hardly

C.sometimes

D.once小题3:

A.promised

B.allowed

C.considered

D.suggested小题4:

A.real

B.hard

C.comfortable

D.rich小题5:

A.sell

B.bring

C.take

D.empty小题6:

A.adapt

B.respond

C.devote

D.lead小题7:

A.would

B.can

C.must

D.may小题8:

A.speak

B.say

C.learn

D.tell小题9:

A.bad

B.well

C.suddenly

D.similarly小题10:

A.failure

B.success

C.effort

D.fame小题11:

A.gain

B.lose

C.save

D.spare小题12:

A.failed

B.began

C.had

D.refused小题13:

A.stupidly

B.carefully

C.slowly

D.quickly小题14:

A.shocked

B.destroyed

C.ruined

D.injured小题15:

A.visit

B.care

C.meet

D.serve小题16:

A.after

B.since

C.before

D.until小题17:

A.joy

B.worry

C.surprise

D.regret小题18:

A.because

B.but

C.or

D.and小题19:

A.sad

B.nervous

C.curious

D.happy小题20:

A.do

B.help

C.feel

D.leave

单项选择题