understanding lift, cont'd

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Home : 2002 : April : 4

understanding lift, cont'd
By Elisabeth

Thanks...your website link was quite helpful. I had appealed for an opinion too to an aeronautical engineer and forwarded his reply to this parent. I am also enquiring to a friend who is a physics graduate.

So, after
thinking too hard about this (!), am I on the right track??
- a pressure difference DOES cause lift (Bernoulli) and can be calculated, provided that velocity variation between the top and bottom of a wing is determined
- this velocity variation can be found for simple shapes using Newton's 3rd law (N3L)
- as the fluid flows around the wing, it is TURNED; this generates a force perpendicular

to the initial flow direction (i.e. LIFT). So when the flow is deflected DOWN, the airfoil is push UP (Newton's 3rd law).

I'm not completely sure I understand why the Equal Transit theory is wrong (but then again I'm not a physics major!) I did see kids using it as an explanation on their quizzes (presumably parents' coaching?). I marked it correct but will spend some time discussing this issue with them tomorrow! (We had just finished studying 'Misconceptions' as a theme in our Space unit so this is apropos!)

Still learning in Canada,
Elisabeth