问题 填空题

在伽利略的时代,技术不发达,无法直接测量自由落体的瞬时速度,伽利略采用了一个巧妙的方法,用来“冲淡”重力.伽利略让铜球沿阻力很小的斜面滚下,得出结论:铜球在斜面上做______运动,进一步科学推理得出结论:自由落体运动是一种______运动,并且所有落体在自由下落时的加速度都______(填“相同”或“不同”).

答案

小球在斜面上由静止释放,受到的阻力很小,故小球做的是初速度为零的匀加速运动;

当物体不受阻力时,只受重力,由静止释放,故做初速度为零,加速度为g的匀加速直线,只要物体只受重力,加速度都相同;

故答案为:初速度为零的匀加速直线 初速度为零,加速度为g的匀加速直线 相同.

阅读理解

Elena jogged (慢跑) with her dad in some empty lots (小块地). These out-of-the-way lots were good places to jog. But the lots were full of rocks and rubbish.

One day, Elena saw a sign on the lots. It said, “New City Park”. Elena was excited. Maybe the park would have a jogging trail (路径)! Elena told her parents about the sign.

“I read about the park in the newspaper,” said Elena’s father. “The city wants volunteers to help clean the area. Then the city will build a soccer field and a playground. But the paper didn’t mention a jogging trail.”

“Well, perhaps if I help clean up the lots, they’ll put in a jogging trail,” said Elena.

On Saturday Elena went to the lots. Many adults were working there. Some were picking up rubbish. Some were moving rocks. Elena looked around. She could carry rubbish, and she could move rocks. So she went to the area every week to do volunteer work. She told everyone she was glad to help build the park. She explained that she hoped the park would have a jogging trail. Then everyone knew her and her jogging trail.

Soon the volunteers cleared the lots. The city could start building. The mayor (市长) gave a speech. He showed a drawing of the new park. He told them about the soccer field. There would be picnic tables. There would be a playground. The park would even have basketball courts. But there was no sign of a jogging trail.

The mayor thanked the volunteers. Then he asked if they had any suggestions. The volunteers said they wanted to build a jogging trail around the park. They told the mayor how helpful Elena had been and how she wanted a jogging trail. The mayor then said, “A jogging trail won’t be hard to build. Let’s do it!”

Everyone clapped and cheered.

小题1:How did Elena know the city needed volunteers to help clean the lots?

A.She read it in the newspaper.

B.She learned it from a sign.

C.She was told by other volunteers.

D.Her father told her about it.小题2:Why did Elena want to help clean the lots?

A.Because she wanted to play on the playground.

B.Because she wanted her name in the newspaper.

C.Because she wanted the city to build a jogging trail.

D.Because she wanted to work with other volunteers.小题3:Who suggested the mayor to build a jogging trail?

A.The volunteers.

B.Elena herself.

C.Elena’s father.

D.Nobody.小题4:What can be the best title for the story?

A.Elena and a Mayor

B.Elena and a Jogging Trail

C.Elena and Some Volunteers

D.Elena’s Family

单项选择题