Pressure differences are created DIRECTLY by the relative motion between fluid and object. That pressure difference is from the relative motion of fluid and object. This force can only be a pressure difference. That force is pressure (difference) and pressure alone.Ī CURVED AIRFLOW requires a force because this is an acceleration. The envelope opens because you blow air into it, thus increasing the internal pressure.Īir has mass and a force is required to accelerate mass (even air). The Bunsen burner is due to entrainment (viscosity). The atomizer (insectide spray) is due to a curved airflow (commonly called "turning" of the air) over the vertical tube's end. If the pressure was lower UNDER the ball it would not be held up. This floating ball explanation is messed up. The lifting paper and tissue paper/leaf blower are a curved airflow followed by entrainment (from viscosity). Paper airplanes (flat balsa wings and Wright Bros wings) have no curved, 'LONGER' upper surface, so this well known bad explanation has a serious problem. Therefore, the pressure in the stream (at its outer boundary) pushes out with the same pressure as the atmospheric pressure outside it pushes inward. Pressure at a point in a fluid acts in all directions can't violate that. If a stream of fast air did have a lower pressure than surrounding air, then, the fast stream would be squeezed narrower and narrower by the higher pressure around it as long as it moved and this simply does not happen. Speed past a surface (or visa versa) does not create a lower pressure. Speed of a fluid DOES NOT create a lower pressure. The true physics is not difficult to understand if you can get all these misconceptions out of your mind. Some of the other comments bring-in many things including math which DOES NOT explain the physics/science. The majority of these demos are classical misinterpretations of the applicable science as well as Bernoulli's actual Principle. And this example, is perfect to reflect over this thesis. Science cannot be taught just based on theory, but it needs to be taught based on observation, something formula and rote-learning cannot teach. The question was, "How would you change the way science is being taught in institutes?" My friend Sahr, wrote this for our team's evaluation form to LUMS PSIFI 2012. Were I to change the way science is taught in institutes, I would encourage appreciation for the implicit over memorisation of the explicit, nurture understanding and curiosity for derivations over worship of formulae, and demonstrate practical applications to clarify ambiguous theory." - Sahr Jalil 2011 What could have been a passion for astrophysics becomes instead distaste for formulae of elliptical orbits students are unable to fully comprehend. However, it is a shame most science students will not realise this during the course of their studies. This is a truth rooted purely in science, one of the many that make the subject beautiful to me. "Look down at the veins tracing their way up your fingers. Please Rate this Instructable and follow me for more cool step by step guides.
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