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Re: [Phys-l] question about Bernoulli



I think all until you get to the spool and card are Coanda effect, but of course I could be wrong. I'm sure on the curveball being the Magnus effect. I'd like to add one:

Fold a sheet of paper in half and set it on a table so it makes a tent. When you blow through the center of the tent, it collapses. However, if you put your mouth right up next to the opening of the tent and blow, there is little effect. I used to think this was the Bernoulli effect, but now I'm pretty sure that's wrong. But what causes the collapse of the tent when your mouth is not right next to the opening?

Bill


William C. Robertson, Ph.D.


On Nov 23, 2010, at 12:14 PM, chuck britton wrote:

How about these examples:
Blowing across the top of a strip of paper held against your lower lip.
Blowing between two balloons that are floating (or suspended)
side-by-side,
close but not touching.
Fabric top of a convertible billowing upwards.
Plastic sheet covering side of double-wide being hauled on
highway billowing outwards.
Two inch square of cardstock with straight-pin thru center,
pin dropped thru hole in spool, blow thru spool to
hold card in place
as you turn the spool over to be blowing downward.

Or perhaps even air flowing faster over the top of an airfoil?????

Spinning balls curve due to the Magnus Effect.