Question

质量为2.0*10³kg的汽车在水平公路上行驶，轮胎与路面间的最大静摩擦力为1.4*

质量为2.0*10³kg的汽车在水平公路上行驶，轮胎与路面间的最大静摩擦力为1.4*10²*²N。汽车经过半径为50m的弯路时，如果车速达到72km/h，这辆车会不会发生侧滑？

Answer 1

速度v=72km/h = 7.2 * 10^4 / 3600s = 20m/s
向心力F= mv^2/r=2.0 * 10^3 kg * (20m/s)^2 / 50m= 1.6 * 10^4 N
轮胎与路面间的最大静摩擦力为 1.4 * 10^4 N < 1.6 * 10^4 N，即会产生侧滑

Answer 2

速度v=72km/h = 7.2 * 10^4 / 3600s = 20m/s
向心力F= mv^2/r=2.0 * 10^3 kg * (20m/s)^2 / 50m= 1.6 * 10^4 N
轮胎与路面间的最大静摩擦力为 1.4 * 10^4 N < 1.6 * 10^4 N，即会产生侧滑赞同7| 评论

Answer 3

Last century, the people most familiar song is the song

from South Lake blue misty rain to Zhongnanhai, the party led us through the eighty-five years of glorious history. In a few days, that is, the anniversary of the National Day Fifty-seven, in this great day, I feel very proud and happy.

reform and opening up, China made great achievements in economic development, GDP average annual growth rate of 9.3%, creating a new world economic miracle. But people have such a common phenomenon: Why comprehensive national strength increased, people's living standards improve, people on the government's satisfaction with the community is on the decline, why many people do not feel happy?

John? Gray in the The size is being accepted by the pleasure we can feel the intensity and number of decisions. Human needs, there are two, one is as inherent in living organisms as food, shelter and other material needs; one is a rational creature as a unique educational and cultural knowledge necessary to meet these two needs are not Previously, people do not get happy. The fundamental difference between good and evil, is that the former increase human happiness, which reduce human being; the ancient Greek philosopher Epicurus said:

Therefore, the mountain stream Concert of Yu Boya is a case of happy, because he found the pure and innocent friendship; emperor call to board the Li Bai is not happy, because he has been wanton unrestrained free; drums and singing into the road basin Zhuangzi is happy, because he is a wise and philosophical sublimation of the idea.

happiness, life satisfaction of citizens. The sum of happiness for all citizens, constitute a Gross National Happiness (GNH, GrossNational Happiness). GNH was first put forward by the King of Bhutan Wangchuk. GDP, economists proposed a different meaning, All of the national policy's ultimate goal is for people to live a happy life.

Here are some data might be able to explain why the people dissatisfied with the status quo:

education. The result of the industrialization of education to universities in China with an annual expenditure of the academic million, enough to make many of the high cost of low-income families put off by the children of college look. At the same time, employment rate remains in the doldrums. 80% in 2002 down to less than 50% in 2005.

medical care. Two decades, rising health care costs a hundred times the number of times the first, much higher than the level of patient income, Rising health care costs, and became a doctor who is morally bankrupt, emerging medical malpractice, quality of service dropped significantly.

housing. Case of Xi'an City, 2000 to 2004, average house prices rose 15.25%. In 2005 the average price of 2871 yuan residential, while the same per capita disposable income of urban residents was 9,627.89 yuan, that is, even without food or drink, a person's annual income can only purchase 3.4 square meters.

results show that, in general, economic growth does improve people's happiness, but can not guarantee rapid economic growth and increasing national happiness, not simply proportional to the straight line between the two relationship, but similar to the law of exponential curve: When the low level of economic development, increase in income can really bring some happiness, and once they reach a certain level of income, began to slow down the effects of happiness. Meanwhile,mac blush, the happiness index is also affected by cultural background, education level, lifestyle and other factors. For example,

results also showed that the current Chinese urban and rural residents of high tuition, high prices,mulberry alexa, high medical expenses patience has been close to the limit. The new three mountains are not Bandiao, will speak of building a socialist harmonious society, most citizens will not have true happiness. Others, such as political reform is slow, increase in crime, government inefficiency, corruption of officials, social inequities and other issues, but also affects people in varying degrees of happiness feelings. Political Sobriety

happiness to the people, economic growth is for the people happy, the development of scientific education and culture or to the people happy, build a harmonious society is for the people happy. Happiness is a most difficult and most human beings want to have wealth. Any access to all means of wealth, this wealth is only happiness is our only goal in life.

present, China has basically solved the problem of food and clothing, is to build a comprehensive well-off society forward. But there are many people who get rich do not feel happy, their spirit did not end, the loss of life to pursue the basic goal. Moreover, the neglect of social justice, leading to the widening gap between rich and poor, the people of the misery index is also growing,Mac cosmetics wholesale, thus planting the hidden social disharmony. Therefore, from the aspects of government decision-making to people's happiness as the goal, requires a scientific development concept and the correct view of achievements, so that citizens receive a more civilized, more progressive, more efficient production and life, to be more and more happiness.

in the 21st century, in today's China, in a materialism and hedonism become popular the world, life and values of the era, we must ask: friends, you happy?