题干

体育课上,小衢和小科进行爬楼梯比赛,从底楼开始爬上9米高的四楼。质量为70千克的小衢用了10秒,质量为60千克的小科用了9秒。小衢说:“我们都从底楼跑到四楼,我的体重比你大,我克服重力做的功比你多”;小科说:“我跑得比你快,我做功的功率比你大”。请通过分析计算说明他们的说法是否正确。

上一题 下一题 0.0难度 选择题 更新时间:2019-12-24 07:22:43

答案(点此获取答案解析)

G小衢=m小衢g=70千克×10牛/千克=700牛

G小科=m小科g=60千克×10牛/千克=600牛

W小衢=F小衢S= G小衢S=700牛×9米=6300焦  

W小科=F小科S= G小科S=600牛×9米=5400焦&nb

同类题5

配对阅读。左栏是五个人的介绍,右栏是七条信息。请将这五个人与他们感兴趣的信息相匹配,并将答案写在相应的位置上。

____Jenny is a pet lover. She wants to work with pets.

____David is the boss of a big education company. He wants to know some information about education in China.

____Wang Lan just came back from England. She is looking for a job. She prefers to work in a big company.

____Helen is a housewife. She wants to buy vegetables and fruit at low prices.

____The students in No.2 Middle School plan to have a picnic. Whether they will do it depends on it will rain or other situations.

A. Lots of people miss their pets while they are on holidays. Our hotel can solve(解决)this problem. We lend cats or dogs to you. We are sure that you will be happy to stay with them.

B. Many people like animals and take them as their pets. Now pet hospitals are very busy .Kind people who love animals are needed to work in busy hospitals.

C. Living in another country can help you to learn a language, and about another culture. Many companies today need employees(雇员)who can speak a foreign language, or have the experience of living or working in another country.

D. We sell eggs, apples tomatoes and pork at very low prices. Our business hours are from 6:00a.m. to 10:30p.m.

E. Our city will have a cloudy day tomorrow .It will be rainy at times. There will be a strong wind. The day after tomorrow will be sunny. It will be a fine day to go hiking or to have a picnic.

F. We have all kinds of video films, TV plays, and music videos. You can enjoy yourself and take time to watch your favorite videos at our shop. You can also borrow some videos home. Each video for a week for 1 dollar.

G. A study of the people in China's largest cities shows that saving money for children's education has become an important reason for saving. It is the second most important purpose of people's saving habit. The result shows that people in China care much about education. The education market is very big in China.