A more thorough analysis of water rockets: Moist adiabats, transient flows, and inertial forces in a soda bottle.

Autor/in	Gommes, C. J.
Titel	A more thorough analysis of water rockets: Moist adiabats, transient flows, and inertial forces in a soda bottle.
Quelle	In: American journal of physics, 78 (2010) 3, S. 236-243 PDF als Volltext Link als defekt meldenVerfügbarkeit
Sprache	englisch
Dokumenttyp	online; gedruckt; Zeitschriftenaufsatz
ISSN	0002-9505; 1943-2909
DOI	10.1119/1.3257702
Schlagwörter	Wasser; Rakete; Physik; Raketenphysik
Abstract	Although water rockets are widely used to illustrate first year physics principles, accurate measurements show that they outperform the usual textbook analysis at the beginning of the thrust phase. This paper gives a more thorough analysis of this problem. It is shown that the air expansion in the rocket is accompanied by water vapor condensation, which provides an extra thrust; the downward acceleration of water within the rocket also contributes to the thrust, an effect that is negligible in other types of rockets; the apparent gravity resulting from the acceleration of the rocket contributes as much to water ejection as does the pressure difference between the inside and outside of the rocket; and the water flow is transient, which precludes the use of Bernoulli's equation. Although none of these effects is negligible, they mostly cancel each other, and the overall accuracy of the analysis is only marginally improved. There remains a difference between theory and experiment with water rockets. © 2010 American Association of Physics Teachers.
Erfasst von	Arbeitsgruppe Didaktik der Physik, Universität Osnabrück
Update	2010/2