IOAA Jr. 2022, Теория, тест с избираем отговор — Задача 4. The Terrestrial Satellite
International Olympiad of Astronomy and Space Sciences for Juniors — Romania– Câmpulung Moldovenesc — October 31 - November 7 2022 — Theoretical Round — I. Multiple choice problems – 100 points · 31 октомври 2022 г.
I. Multiple choice problems – 100 points
For these problems, you have to choose only one correct answer. Please write your answer on answer-sheet. Don’t forget to write the number of the problem, i.e Grid 1. (c).
Условие
A small satellite (a luminous sphere) that orbits the Earth, in an equatorial circular orbit at the altitude , is photographed with a camera on the ground, the lens of which is a converging lens with focal length . The photography is made when the satellite aligns with the camera and the centre of the Earth.
It is given: the mass of the Earth, ; the gravitational constant, G, the radius of the Earth, R. During the photographic exposure the proper rotation of the Earth is neglected.
The length of the image on the photograph, after developing the photographic plate, placed in the focal plane of the objective lens, as indicated by the drawing in figure 1, if the exposure time of the camera was , is given by the expression:
a)

b)
c)
d)
Отговори
- a)
Решение
Sector AB, in the circular orbit of the satellite, represented in the drawing in Figure 2, traveled by the satellite during the time , equal to the exposure time of the camera, has the length:

where – the speed of the satellite in its circular orbit, relative to the center of the Earth;
Because the distance between the satellite and the camera lens is very large, the image will be formed in the focal plane of the camera lens.
Since the circle sector AB is very short and has a very large radius , it can be assimilated with the line segment AB, so that:
where – the length of the image on the photo;
Оригинал в Архива: Multiple_Choice.pdf · официални решения: Grid_1.pdf · допълнителни данни: Grid_2.pdf · допълнителни данни: Grid_3.pdf · допълнителни данни: Grid_4.pdf · допълнителни данни: Grid_5.pdf · допълнителни данни: Grid_6.pdf · допълнителни данни: Grid_7.pdf · допълнителни данни: Grid_8.pdf · допълнителни данни: Grid_9.pdf · допълнителни данни: Grid_10.pdf