问题 填空题

在做“互成角度的两个共点力的合成”实验时,橡皮筋的一端固定在木板上,用两个弹簧测力计把橡皮筋的另一端拉到某一确定的O点,以下操作中正确的是 (  )

A.同一次实验过程中,O点位置允许变动

B.实验中,弹簧测力计必须保持与木板平行,读数时视线要正对弹簧测力计刻度

C.橡皮筋应与两绳夹角的平分线在同一直线上

D.实验中,把橡皮筋的另一端拉到O点时,两个弹簧测力计之间夹角应取90°,以便算出合力大小

答案

A、本实验研究合力与分力的关系,合力与分力是等效的,同一次实验过程中,O点位置不能变动,以保证橡皮筯伸长的长度相同,效果相同.故A错误.

B、本实验是通过在白纸上作力的图示来验证平行四边定则,为了减小实验误差,弹簧秤、细绳、橡皮条都应与木板平行,否则,作出的是拉力在纸面上的分力,误差较大.读数时视线必须与刻度尺垂直,防止视觉误差.故B正确.

C、只要橡皮筋的另一端两次都接到O点,达到效果相同,拉力方向没有限制,橡皮筋不需要与两绳夹角的平分线在同一直线上,故C错误.

D、本实验只要使两次效果相同就行,两个弹簧称拉力的方向没有限制.故D错误.

故选B.

阅读理解

Lexi Peters, a 14-year-old girl in New York, loves hockey. She’s not only good at playing on her after-school team, but also at playing hockey video games. But when Peters played the popular NHL (National Hockey League) games made by Electronic Arts, something really bothered her. The virtual (虚拟的) character in the game could only be a boy — not a girl.

She didn’t think that was reasonable. There must be many girls playing hockey in the US. So she wrote a letter to Electronic Arts.

“Being represented by a man is unfair to women and girl hockey players,” Peters wrote. “Women’s hockey is a fast-growing sport. I am confident that I’m not the only woman interested in the opportunity to create herself in the game.”

Several weeks later, Peters received an unexpected e-mail from the senior producer for EA Sports’ NHL games, David Littman. “Hi, Lexi,” the e-mail began. “We agree with you!”

Electronic Arts said it would create a female player in the game. “I was thinking you could be the model,” Littman wrote. Peters almost couldn’t believe it. Later, she sent photos of herself taken at all different angles (角度).

And so, when Electronic Arts released the newest version of their game, NHL 12, this fall, Peters was the face of the female player. She can now skate with the NHL’s great players. “It’s strange at first, but you get used to it,” said Peters. “It’s really funny and cool.”

For Peters, there is also an important lesson that she will take with her the rest of her life. “If you have something to say, and you think it’s important, go for it!” she said.

小题1:What bothered Peters when playing NHL games?

A.There was no girl character in the game.

B.The characters were not real at all.

C.No girls would like to play the game.

D.It was not like playing real hockey games.小题2:According to Peters’ letter, we can know that ________.

A.girls were not allowed to play hockey in the past

B.female players can be represented by men

C.boys don’t like to play hockey with girls

D.more and more girls are interested in hockey小题3:What was David Littman’s opinion of Peters’ letter?

A.He ignored it.

B.He disliked it.

C.He agreed to it.

D.He voted against it.小题4:Peters’ experience tells us that we should ________.

A.enjoy the fun of being a model

B.do what you think important to do

C.work hard to get used to any new situation

D.think about problems from different angles

名词解释