问题 选择题

在检测某款电动车性能的实验中,质量为8×102kg的电动车由静止开始沿平直公路行驶,达到的最大速度为15m/s。利用传感器测得此过程中不同时刻电动车的牵引力F与对应的速度v,并描绘出F—1/v图像(图中AB、BO均为直线),假设电动车行驶中所受的阻力恒定,则(               )

 

(A)在全过程中,电动车在B点时速度最大 

(B)电动车作匀加速运动时的加速度为2m/s2

(C)电动车的额定功率为6kw

(D)电动车作匀加速运动所需的时间为1.5s

答案

B、C、D

在全过程中,电动车在C点时速度最大,A错。电动车速度最大时牵引力与阻力相等,即阻力f=400N,根据牛顿第二定律计算可得,B对。电动车的额定功率,C对。电动车作匀加速运动的最大速度则所需的时间为,D对

阅读理解

阅读理解。

     When I was in Grade Four, Mr Stamps took us to a place called Camp

Noria to go camping.

     When we arrived at the camping, we took a walk in the forest. Then we

had a difficult project: to build a small house in the forest After the project

was finished the sky was dark, then We return to the campsite to have supper.

     We roasted (烤) hotdogs on the bonfire(篝火). The botdogs smelled good! Some of the other food was not that good. After supper everybody played a game of tag(捉人游戏).  It was very cold at night and the next morning

everybody was awake very early.

     Around noon time, the sun rose up. We took turns riding a small horse.

When starting to ride it, I was scared, but after being on it for some time, I

felt that it was fun. In the afternoon we went to row canoes(划独木舟).

Since this was my first time doing these activities, I felt very excited.

     On the third day we returned home. I hope to go back there next year.        

1. How did the writer like the camping?

A. The writer enjoyed it a lot.

B. The writer was afraid of camping.

C. The writer disliked Camp Noria.

D.  It was a little boring.

2. Which of the following activities did the writer and his friends do first

during the camping?

A. Built a small house.    

B. Played a game of tag.

C. Rode horses.        

D. Rowed canoes.

3. What did the writer think of the hotdogs?

A. The writer roasted them.

B. The writer enjoyed them.

C. Not that tasty.

D. They were burned.

4. How long did they camp?

A. Two days.            

B. Three days.

C. Four days.            

D. A week.

5. Which statement is TRUE according to the passage?

A. It didn't take them a long time to build a small house in the forest.

B. All the food they cooked over the bonfire was delicious.

C. It was very cold at night and they all woke up early the next morning.

D.The writer was good at riding a horse and enjoyed it a lot.

问答题 简答题