IYPT 1991, Задачи на турнира — Задача 9. Passive motor
Problems for the 4th International Young Physicists’ Tournament
Critical edition
Olympiets Youth Center, Moscow, Soviet Union; July 22‒28, 1991 [1]
Critical edition: translated, restored, and commented text [2]
FINAL DRAFT. — Please do not re-publish. Suggestions and criticism welcome
Translated, edited and commented by Ilya Martchenko. The original edition’s historical notes, sources and acknowledgments are retained with problem 1.
Епиграф
Is this black currant?
No, it is red currant.
But why is it white?
Because it is still green. [3]
Условие
An apple dropped [15] from a balcony of a multi-storey building will calmly descend into the hands of your friend, if you attach to the apple a propeller cut out of dense paper [16]. Explain the principle of work for such a parachute and study the dependence of the drag force on the descent rate and on the sizes of the propeller’s blades.
Note [15]
The original Russian text is ambiguous, as the word «брошенный» can imply both the release without initial speed and the launch in the air under any angle
Note [16]
The 1992 Czech and the Slovak texts read, “rigid paper”, and specify that the propeller “is attached to this apple with a match”
Решение
Внимание: Непълно решение
В архива няма официално решение на тази задача.
Оригинал в Архива: 1991.pdf