Съдържание

Условие Note [18]Note [19]Note [20]Решение

IYPT 1989, Задачи на турнира — Задача 12. Sand in a tube

Оригинал на условието (PDF)Съобщи за грешка

Всички материали от IYPT 1989

Problems for the 2nd International Young Physicists’ Tournament

Внимание: Бележка към темата

The original header prints 1988, although this is the 2nd IYPT problem set for 1989; the edition’s note [1] and its bibliography identify the 1989 event. The printed header is retained.

Critical edition

Olympiets Youth Center, Moscow, Soviet Union; March 24‒April 2, 1988 [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

Squamps are hunted from the inside only.
S. Lem [3]

Условие

A glass tube is installed vertically and its lower end is tightly closed with a cap. [19] The tube is filled with some sand. During what time $T$ will the sand flow out of the tube, when the cap is opened? Investigate the dependence of $T$ on the following parameters: size of sand grains $d$ , length of the tube $L$ , diameter of the tube $D$ , [20] at a constant degree of packing of sand (you have to introduce and validate this parameter on your own.) We ask you not to consider high degrees of packing for comparability of the results. It is preferred that $10\,\mathrm{cm}<L<1\,\mathrm m$ .

Note [18]

A different problem at the Correspondence Round [Kvant 1988]: “Weather forecast. “A fall of a barometer means bad weather” ― why this statement is most often correct?” In [Jordens 1989], the problem reads: “The weather forecast. Barometer falling means bad weather. Why this is usually valid?”

Note [19]

The original Russian text is ambiguous, as the word «заслонка» can mean both a flat cap and a butterfly valve, which would imply more tunable parameters to investigate. Despite the wording «открыть заслонку» (open, not remove the item in question), it may be speculated that a device capable of throttling flow would be discussed in much more detail and its parameters would be introduced in the problem itself, similarly to the parameters of the glass tube. “Closed with a valve”, according to the 1996 Czech and the 2006 English text. Just “tightly closed”, according to the Slovak text

Note [20]

The parameter “diameter of the tube D” does not appear in the Slovak text. The 2006 English text names it “diameter of the tube B”

Решение

Внимание: Непълно решение

В архива няма официално решение на тази задача.

Оригинал в Архива: 1989.pdf