Saturday, February 14, 2015

Physics behind airplanes vs rockets

Fr. Cedric makes common mistake of conflating physics behind airplane motion, i.e. Bernoulli's equation, with that of rockets, i.e. Newton's 2nd law of Motion:


Rocket propulsion uses Newton's 2nd Law of Motion: Law of Conservation of Linear Momentum, and thus can operate in the vacuum of space. From a standard introduction to physics text:  Serway, Raymond A., Robert J. Beichner, and John W. Jewett, Jr. Physics For Scientists and Engineers. Fifth ed. New York: Saunders College, 2000. 

Conversely, aeroplanes operate under Bernoulli's principle and require the presence of a fluid, as scientists would say, or air, as common folks would, and thus planes can't fly in the vacuum of space:

Additionally, whilst on physics, the moon is neither a planet nor a star but is a natural satellite. Even Dish Nation goofs on the lack of scientific knowledge of their home shopping network compadres:


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