Барометрическая формула. Devastatingearthquake in China’s northwestern Xinjiang region haskilled at least 259 people, injured2000 others

Devastatingearthquake in China’s northwestern Xinjiang region haskilled at least 259 people, injured2000 others. Officials say Monday’squakeflattenedthousands of homes, schools, and buildings in a predominantly Muslim area near China’s mountainousborder with Kyrgyzstan and Tajikistan. Powerfulquake measured 6.8 on the Richterscale. Rescuecrews and soldiers havebeensearching the rubble for survivors and bodies. And authorities expect the deathtolltorise.

(VOA February, 2003)

 

News 108

The leaders from sportsorganisations and governments around the world aremeeting in the DanishcapitalCopenhagen today todiscuss the introduction of an international codetotackle the use of banneddrugs in sport. The new anti - dopingcode would unify the fight against drugsacross all sports in all countries. Here is our sports correspondent H.P.

At the moment some sportsfederations have different sanctions for dopingoffenders while others arefearfulofactions in civilcourts. The world anti - dopingcode is designed to getridofanomalies and provide a unified stance against drug cheats. The head of the agency D.C. accepts that the code isn’t perfect but couldprovide a major breakthrough. He admits that thereareareas where agreement isnotyetpossible.

The United States hasresisteddopingcontrols for its major professional sports: baseball, basketball, ice- hockey, and Americanfootball.

And some federations are not happywith a two - yearsanctions for a first offence.

(BBC March, 2003)

 

News 109

Adayafter scientists in Italy said that aspirincouldhelppreventcancers of mouth and throat, American researchshowed the drug could significantly help reduce the chances of people developingcoloncancer, the second leadingcause of cancerdeaths in the United States. Scientists in New Hampshire and Chicago say their studiesindicate that regular useofaspirin can reduce the risk of pre - cancer’sgrowths in the colon, which often lead to bowelcancer.

(BBC March, 2003)

 

News 110

CostaRicahasoffered political asylumtoone of Venezuela’s mostprominent opposition leaders Carlos Ortega, whosought refuge in its embassy in the Venezuelan capital Caracas. Mr. Ortega, who wasinstrumentalinorganising a two - monthlong general strike against President Chavez, hadbeeninhiding after beingchargedwithtreason and rebellion. Hundreds of opposition demonstratorsgathered around the embassy to express their supportfor Mr. Ortega. The Venezuelan Interior Minister Luis Miquilena said the government wouldgrant him safepassageoutof the country.

(BBC March, 2003)

Барометрическая формула

При выводе основного уравнения МКТ и распределения Максвелла предполагалось, что внешние силы не действуют, поэтому молекулы равномерно распределены по всему выделенному им объему. В земной атмосфере плотность воздуха с высотой уменьшается, давление падает.

Найдем , т.е. p как функцию h.

Считаем, что поле тяготения однородно, температура постоянна (опять натяжка), масса молекул одинакова.

 

p₂ – гидростатическое давление

 

p+dp

∆h

P

 

h₂

h

 

p₁

 

h₁

 

 

Разность давлений p и (p+dp) равна весу газа, в столбе высотой h и площадью основания равной 1м².

изменением на пренебрегаем

, т.к (М – молярная масса)

или и

или, потенцируя, , если взять на уровне моря – , давление , то

– барометрическая формула.

Т.к. : – т.к , то изменение концентрации молекул с высотой, т.е. чем тяжелее газ, тем его давление с высотой меняется быстрее.