问题 实验题

(1)如图所示,一竖直弹簧下端固定于水平地面上,小球从弹簧的正上方高为h的地方自由下落到弹簧上端,经几次反弹以后小球落在弹簧上静止于某一点A,则(   )

A.h愈大,弹簧在A点的压缩量愈大

B.弹簧在A点的压缩量与h无关

C.小球第一次到达A点时的速度与A位置无关

D.h愈大,小球第一次到达A点时的速度愈大(2)在探究功与速度关系实验中为什么要把小木板一端垫高                   ?          

答案

(1) BD  (2)平衡摩擦力

题目分析:(1)小球落在弹簧上静止于某一点A,说明在A点重力与弹簧的弹力二者平衡,所以.弹簧在A点的压缩量与h无关,故A错误,B正确;A点的高度一定,由机械能守恒定律可知, h愈大,小球第一次到达A点时的速度愈大,故C错误,D正确;

(2)小车下滑时受到重力、拉力、支持力和摩擦力,要使拉力等于合力,拉力做功等于合力做功,则应该用重力的下滑分量来平衡摩擦力,故可以将长木板的一段垫高。

阅读理解

There was once a blind man, who did a lot of traveling alone. He was making his first trip to Texas and happened to be seated next to a Texan on the flight.

The Texan spent a lot of time telling him how everything was bigger and better in Texas. After the blind man reached his destination, a large resort (度假) hotel, he was very excited about being in Texas.

The long trip had worn him out a little so he decided to stop at the bar for a small soda and a light snack before going up to his room to sleep.

When the waitress set down his drink, it was in a huge cup. “Wow, I had heard everything in Texas is bigger,” he told her.

“That’s right,” she replied. The blind man ate his snack and finished his drink. After drinking such a large amount, it was natural that his next stop was to be the restroom. He asked the waitress for directions. She told him to turn left at the corner, and then take the second door on the right.

He reached the first door and continued. A few steps later he stumbled (绊倒) slightly and missed the second door and ended up going through the third door instead. Not realizing he had entered the swimming area he walked forward and immediately fell into the swimming pool.

Remembering that everything was bigger in Texas, he had his head above water and started shouting “Don’t flush(冲洗)! Don’t flush!”

小题1:Why was the blind man excited about being in Texas?

A.It was the first time that he had travelled abroad.

B.People from Texas were very friendly than he expected.

C.He heard that everything was bigger and better in Texas.

D.The service staff in the large resort hotel was very humorous.小题2: Why did the blind man enter the swimming area?

A.He wanted to go swimming.

B.He wanted to have a bath.

C.He stumbled and missed the restroom door.

D.The waitress gave him wrong directions.小题3: Why did the blind man go to the bar?

A.To go through it on his way to his room.

B.To have a short rest after a long walk.

C.To have something to eat there.

D.To ask a waitress for directions.小题4: Why did the blind man shout out “Don’t flush! Don’t flush!”?

A.He thought he was caught in a big toilet and someone was cleaning it.

B.He didn’t want anyone to clean the toilet at that time.

C.He didn’t want anyone to clean the swimming pool at that time.

D.He thought it was such a big swimming pool that making it clean was no use.小题5:If the passage is taken from a website, which part of the website does it belong to?

A.Travel services.

B.Hotel services.

C.Funny stories.

D.Health problems.

多项选择题