问题 填空题

小明将重30N的球举高1.5m,再用20N的力将球推出,球落地后又滚动了5m停下,则小明将球举高的过程中对球做的功是______J;球在地面滚动的过程中,人对球所做的功是______J.

答案

①W=Gh=30N×1.5m=45J.

故答案为:45.

②球在地面滚动的过程中,虽然有距离,但是人没有力作用在物体上,所以人对球没做功.

故答案为:0.

单项选择题
阅读理解

阅读理解。

     When you are little, the whole world feels like a big playground. I was living in Conyers, Georgia the

summer it all happened. I was a second grader, but my best friend Stephanie was only in the first grade.

Both of our parents were at work and most of the time they let us go our own way.

     It was a hot afternoon and we decided to have an adventure in Stephanie's basement. As I opened the

basement door, before us lay the biggest room, full of amazing things like guns, dolls, and old clothes. I

ran downstairs, and spotted red steel can. It was paint. I looked beyond it and there lay even more paint

in bright colors like purple, orange, blue and green.

     "Stephanie, I just found us a project for the day. Get some paintbrushes. We are fixing to paint." She

screamed with excitement as I told her of my secret plans and immediately we got to work. We gathered

all the brushes we could find and moved all of our materials to my yard. There on the road in front of my

house, we painted bit stripes (条纹) of colors across the pavement (人行道). Stripe by stripe, our colors

turned into a beautiful rainbow. It was fantastic!

     The sun was starting to sink. I saw a car in the distance and jumped up as I recognized the car. It was

my mother. I couldn't wait to show her my masterpiece. The car pulled slowly into the driveway and from

the look on my mother's face, I could tell that I was in deep trouble.

     My mother shut the car door and walked towards me. Her eyes glaring, she shouted, "What in the world

were you thinking? I understood when you made castles out of leaves, and climbed the neighbors' trees, but

this! Come inside right now!" I stood there glaring hack at her for a minute, angry because she had insulted

(侮辱) my art.

     "Now go clean it up!" Mother and I began cleaning the road. Tears ran down my cheeks as I saw my

beautiful rainbow turn into black cement.

     Though years have now passed, I still wonder where my rainbow has gone. I wonder if, maybe when

I get older, I can find my rainbow and never have to brush it away. I guess we all need sort of rainbow

to brighten our lives from time to time and to keep our hopes and dreams colorful.

1. What did the writer want to do when his mother came home?

A. To introduce Stephanie to her.

B. To prevent her from seeing his painting.

C. To put the materials back in the yard.

D. To show his artwork to her.

2. In his mother's eyes, the writer _____.

A. was a born artist

B. always caused trouble

C. was a problem solver

D. worked very hard

3. The underlined word "rainbow" in the last paragraph refers to _____.

A. the rainbow in the sky

B. the stripes on the pavement

C. something imaginative and fun

D. important lessons learned in childhood

4. It can be learned from the passage that parents should _____.

A. encourage children to paint

B. value friendship among children

C. discover the hidden talent in children

D. protect rather than destroy children's dreams