IAO 2009, Теория, Група α — Задача 2. Number of molecules.
Theoretical round. Problems to solve · 8 ноември 2009 г.
Бележка
Maybe not all problems have correct questions. Some questions (maybe the main question of the problem, maybe one of the subquestions) may have no real sense. In this case you have to write in your answer (in English or Russian): “impossible situation – ситуация невозможна”. Of course, this answer has to be explained numerically or logically.
Data from the table of planetary data may be used for solving every problem.
The answers «Да-Yes» or «Нет-No» has to be written in English or Russian.
Note for jury and team leaders.
The proposed sketches are not full: the team leaders have to give more detailed explanations for students. But the correct solutions in the students’ papers (enough for 8 pts) may be shorter.
Parameters of orbits. Physical characteristics of some planets, Moon, Sun and Eris
| Body, planet | Average distance (astr. units) | Average distance (mln. km) | Sidereal period (troph. years) | Period (days) | Eccentricity | Equat. diameter (km) | Mass ( kg) | Av. density (g/cm³) | Grav. acceler. (m/s²) | Max. magn. from Earth | Albedo |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Sun | 1392000 | 1989000 | 1.409 | ||||||||
| Mercury | 0.387 | 57.9 | 0.241 | 87.97 | 0.206 | 4879 | 0.3302 | 5.43 | 3.70 | 0.06 | |
| Venus | 0.723 | 108.2 | 0.615 | 224.70 | 0.007 | 12104 | 4.8690 | 5.24 | 8.87 | 0.78 | |
| Earth | 1.000 | 149.6 | 1.000 | 365.26 | 0.017 | 12756 | 5.9742 | 5.515 | 9.81 | 0.36 | |
| Moon | 0.00257 | 0.38440 | 0.0748 | 27.3217 | 0.055 | 3475 | 0.0735 | 3.34 | 1.62 | 0.07 | |
| Mars | 1.524 | 227.9 | 1.880 | 686.98 | 0.093 | 6794 | 0.6419 | 3.94 | 3.71 | 0.15 | |
| Jupiter | 5.204 | 778.6 | 11.862 | 4332.59 | 0.048 | 142984 | 1899.8 | 1.33 | 24.86 | 0.66 | |
| Saturn | 9.584 | 1433.7 | 29.458 | 10759.20 | 0.054 | 120536 | 568.50 | 0.70 | 10.41 | 0.68 | |
| Eris | 68.01 | 204862 | 0.434 | 2600 | 0.0167 | 0.8 | 0.86 |
**) For Moon: in mean opposition.
Some constants and formulae
| Constant or formula | Value |
|---|---|
| Speed of light in vacuum, (m/s) | 299792458 |
| Constant of gravitation, (N·m²/kg²) | |
| Solar constant, (W/m²) | 1367 |
| Hubble constant, (km/s/Mpc), mean value | 70 |
| Hubble constant, diapason of values | 50–100 |
| Plank constant, (J·s) | |
| Charge of electron, (C) | |
| Mass of electron, (kg) | |
| Proton-to-electron ratio | 1836.15 |
| Faraday constant, (C/mol) | 96485 |
| Magnetic constant, (H/m) | |
| Universal gas constant, (J/mol/K) | 8.314 |
| Boltzmann constant, (J/K) | |
| Standard atmosphere (Pa) | 101325 |
| Stefan-Boltzmann constant, (W/m²/K⁴) | |
| Wien's displacement constant, (m·K) | 0.002897 |
| Laboratory wavelength of H (Å) | 6563 |
| Refractive index of water for20°C, | 1.334 |
| Area of sphere | |
| 3.14159265 |
Data of some stars
| Star | Designation | RA | DEC | m | SC |
|---|---|---|---|---|---|
| Arcturus | Boo | -0.05 | K1 | ||
| Vega | Lyr | 0.03 | A0 | ||
| Deneb | Cyg | 1.25 | A2 | ||
| Polaris | UMi | 2.02 | F7 | ||
| Sirius | CMa | -1.46 | A1 |
Бележки от източника
The original two-up official key photographs clip some right-hand line endings. Ellipses mark those unreadable endings; visible formulae and printed numerical values are retained. The reference table gives the Eris period as 204862 days, whereas the key uses 204852 days. Original inline slash notation is retained in the key. The photographed alpha masthead is cropped, but the original filename and distinct alpha tasks in the official key establish its group.
Условие
Estimate the number of molecules in the Earth's atmosphere.
Решение
The pressure of an atmosphere is the total weight of all number () of its molecules, distributed over the whole surface of a planet, that is,
where is the mean value of mass of molecules in atmosphere. Taking into account that the surface of the Earth is
and mass of molecule is
where is Avogadro number, we can write
Since the Earth atmosphere consists mostly on N () and O () in approximate proportion 3:1, the mean value of is 29 g/mol or in SI: . Calculations:
Оригинал в Архива: alphatheo.png · допълнителни данни: theosol1.jpg · допълнителни данни: theosol2.jpg · допълнителни данни: constants.jpg