Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: The Bernoulli Theory of Flight

Learn more physics!

Most recent answer: 09/11/2014
Q:
Did you know that the Bernoulli theory of flight is Baloney? The actual Bernoulli lift of a Cessna 152 at landing speed is about 42 pounds. The rest is Newton. The wing hump effeciently and effectively deflects air downward. Action/Reaction. Newton. Please check out the following website. http://www.aa.washington.edu/faculty/eberhardt/lift.htm
why people cheat catch a cheat how many people cheat
hillcrest abortion clinic stories of abortion live abortion video
the best android phone link phone tracking apps
types of abortions read what happens when you get an abortion
free prescription cards go walgreens prints coupon codes
married cheaters site dating for married men
priligy 30mg go cialis 40mg
ventolin 2mg thyroxine 25mcg deltasone 40mg
online discount pharmacy dotnetblogengine.net coupon for prescription
prescriptions coupons markthrice.com discount coupon for viagra
new prescription coupon areta.se prescription coupon card
can i take antabuse and naltrexone can i take antabuse and naltrexone can i take antabuse and naltrexone
acheter viagra pas acheter viagra pas acheter viagra pas
naproxennatrium click naproxen migraine
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
niacine movidafm.net niacin v hrani
diflucan 150 site diflucan sirup
proscar vs propecia for hair loss read proscar pris

- Ron Wyett (age 52)
Baltimore, MD
A:
Ron -

The Bernoulli theory of flight is most certainly not 'Baloney.' It is, as the website that you refer to points out, a well-proven phenomenon of air dynamics that is present and should be accounted for in all flight calculations. Nor is its influence the same for all planes.

For the Cessna 152 that you refer to, its net contribution to lift is extremely small. In some older planes, the Bernoulli effect played a very significant role, however, and it is possible to design light-weight model planes that rely almost entirely upon it.

The most common description of the Bernoulli theory of flight that I have heard of indicates that the Bernoulli effect is 'part' of what allows airplanes to fly. It is also one of the elements of lift that is accessible to younger students who may not have in-depth understandings of fluid mechanics and the dynamics of flight. For this reason, it is commonly taught, and its validity should not be denied. However, it is true that there are numerous other factors that influence the total lift felt by an airplane, and the site that you referenced gives a very good description of them.

-Tamara
hillcrest abortion clinic abortive live abortion video
the best android phone how to spy on cell phones phone tracking apps
internet drug coupons open prescription coupon
best android spy apps to spy on phones how to spy on an android phone
discount card prescription damske.com print cvs
finasteride zithromax cialis 80mg
coupon for viagra modelosguayaquil.com viagra discount coupons online
discount prescriptions coupons mba-institutes.com internet drug coupons
acheter viagra pas acheter viagra pas acheter viagra pas
cialis coupons from lilly prescription drug cards coupons for prescriptions
discount prescription drug cards nationalautocare.com prescription discounts cards
arcoxia 30 arcoxia 90 arcoxia wiki
seroquel 25 mg site seroquel debljanje

(published on 10/22/2007)

Follow-Up #1: Bernoulli?

Q:
You have just proved then that an aeroplane can not fly upside down. The Bernouilli effect is almost negligible in determining lift - see other websites for the complete explanation Try the link below. www.aviation-history.com/theory/index-theory.html
married men cheat with men open wifes cheat
types of abortions site what happens when you get an abortion
buy sildenafil 100mg viagra without a doctor prescription viagra 100 mg
ventolin 2mg bistromc.org deltasone 40mg
imitrex 50mg thepoliticalsword.com flagyl 200mg
viagra coupons from manufacturer open drug discount coupons
prescription drugs coupons click viagra coupon card
coupons for prescriptions floridafriendlyplants.com prescription drugs discount cards
pfizer coupons for viagra viagra coupon viagra discounts coupons
acheter viagra pas acheter viagra pas acheter viagra pas
acheter viagra pas acheter viagra pas acheter viagra pas
where buy viagra online http://viagraforsaleuk1.com online viagra buy
cialis price online lipseysguns.com cialis price history
coupons for prescriptions discount prescription coupons drug prescription card
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
niacine movidafm.net niacin v hrani
cialis cialis cialis walgreen coupon
fluvoxamine (luvox) blog.tgworkshop.net fluvoxamina bula
cefdinir red stool ski-club-auringen.de cefdinir nedir
renovacija stanovanja click renova g
lasix injetavel lasix lasix

- Andrew (age 57)
Australia
A:
Andrew- I think you've misread Tamara's answer. Some planes, not all, rely significantly on the Bernoulli effect. Those planes cannot fly upside down. Ones that can fly upside down obviously use little or no Bernoulli effect.

BTW, even when the Bernoulli effect is important, the standard popular descriptions of how it works for planes are wrong. It is not true that the air flowing over the top part of the wing has to arrive at the rear of the wing at the same time as the air flowing over the bottom.

The URL you cite looks very good.

Mike W.
why people cheat infidelity signs how many people cheat
internet drug coupons site prescription coupon
discount card prescription damske.com print cvs
coupons rx prostudiousa.com www.januvia.com coupons
imitrex 50mg site flagyl 200mg
viagra coupons from manufacturer liberitutti.info drug discount coupons
new prescription coupon areta.se prescription coupon card
coupons for prescriptions new prescription coupons prescription drugs discount cards
1 wk pregnant abortion pill article on abortion
diabetes affect sexuality open diabetes sexuality treatment
diabetes affect sexuality cialis dosage information diabetes sexuality treatment
cialis manufacturer coupon link prescription drug coupons
claritinekombo warpedfish.co.uk claritine za psa
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
naprosyn roche rileytech.net naprosyn nedir
champix alkohol mdwguide.com champix
champix alkohol click champix
kamagra wikipedia blog.jrmissworld.com kamagra shop
flibanserin online flibanserin buy flibanserin buy
sildenafil pfizer link sildenafil sandoz
cialis cialis cialis walgreen coupon
voltaren retard voltaren pomada voltaren spray
cialis coupon card evans.com.mx cialis coupon
prescriptions coupons coupons for prescriptions drug prescription card
vivitrol alcohol what is vivitrol shot narcan challenge

(published on 08/26/2008)

Follow-Up #2: Bernoulli pedagogy

Q:
If the Bernoulli principle is only a small part of lift and is only significant in limited situations, wouldn't it be a much better approach to instead explain lift in terms of something that is always correct? For example, Newton's principles embodied in his 3 laws are as accessible to kids (actually much more so) than Bernoulli's principle, they are easily demonstrated, and wing lift can always be explained in terms of these principles. Pressure, force, lift, angle of attack, e.g., all make mores sense in light of Newton's 3 laws and is much more teachable as well. As a teaching tool, I see little benefit in always pushing a principle that, while applicable under certain circumstances, avoids the reals reasons why most airplanes fly. All one has to do is look at the airfoil of a 747 or even the Wright Flyer and appeals to Bernoulli seem untenable.
types of abortions the weeks of pregnancy what happens when you get an abortion
abortion pill clinics abortion pill prices for abortions
diprolene go furosemide 40mg
priligy 30mg go cialis 40mg
finasteride sigridw.com cialis 80mg
free online coupons onlineseoanalyzer.com new prescription coupons
free online coupons pharmacy coupon new prescription coupons
prescriptions coupons markthrice.com discount coupon for viagra
viagra coupons from manufacturer open drug discount coupons
new prescription coupon areta.se prescription coupon card
pfizer coupons for viagra viagra coupon viagra discounts coupons
diabetes affect sexuality cialis dosage information diabetes sexuality treatment
viagra bestellen online viagra pillen kruidvat pillen kopen
where buy viagra online http://viagraforsaleuk1.com online viagra buy
cialis manufacturer coupon cialis discounts coupons prescription drug coupons
cialis coupon lilly blog.nvcoin.com transfer prescription coupon
lilly cialis coupon prostudiousa.com coupons prescriptions
lilly cialis coupon click coupons prescriptions
naproxennatrium site naproxen migraine
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
augmentin générique arbot.cz augmentin sirop
fusidinezuur kopen go fusidic acid
diflucan 150 diflucan djelovanje diflucan sirup
kamagra wikipedia kamagra jelly kamagra shop
cialis open cialis walgreen coupon
amlodipine 5 mg amlodipine bijwerkingen amlodipine accord
allods online cwblog.centralworld.co.th allo allo
singulair 4 mg granulat scottdangelo.com singulair patient information
cialis coupon card evans.com.mx cialis coupon
vivitrol alcohol what is vivitrol shot narcan challenge

- John Strong (age 43)
Lindenhurst, IL USA
A:
I tend to agree.

I wouldn't distinguish, however, between Newton's laws and the Bernoulli principle. The Bernoulli principle is one particular phenomenon within that framework. I think the real distinction you want to make is between the simple push provided by wind on a tilted surface and the more complicated Bernoulli effect. Both are plain Newtonian forces.

Mike W.
why people cheat catch a cheat how many people cheat
the best android phone mealmixer.com phone tracking apps
internet drug coupons coupons for prescription medications prescription coupon
abortion pill clinics abortion pill prices for abortions
free prescription cards nwwebdesigns.net walgreens prints coupon codes
finasteride sigridw.com cialis 80mg
online discount pharmacy viagra coupons and discounts coupon for prescription
prescriptions coupons go discount coupon for viagra
prescription drugs coupons viagra manufacturer coupon 2016 viagra coupon card
viagra coupon card free prescription cards discount viagra free coupon
prescription discount coupons free prescription drug cards viagra discount coupons online
can i take escitalopram in the morning can i take escitalopram in the morning can i take escitalopram in the morning
can i take minocycline with birth control read can i take minocycline with birth control
diabetes affect sexuality diabetes sexuality treatment
claritinekombo warpedfish.co.uk claritine za psa
fusidinezuur kopen blog.jp-sa.org fusidic acid
diflucan 150 site diflucan sirup
ibuprofen rapid ibuprofen spc ibuprofen
seroquel 25 mg click seroquel debljanje
seroquel 25 mg click seroquel debljanje
buscopan hund go buscopan dragees
voltaren retard voltaren pomada voltaren spray
voltaren retard voltaren forte voltaren spray
singulair 4 mg granulat scottdangelo.com singulair patient information
prescriptions coupons emergent-ventures.com drug prescription card

(published on 10/11/2009)

Follow-Up #3: Bernoulli effect and gas expansion

Q:
When a parcel of air speeds up then it stretches out so that pressure decreases in accordance with Bernoulli principle. ( http://www.boeing.com/companyoffices/aboutus/wonder_of_flight/airfoil.html ). But when air enters a narrow valley from an open field , it speeds up. So according to Bernoulli principle the pressure in narrow valley should be lower. Thus in first case spreading out of air decreases pressure while in 2nd case compressing decreases the pressure . How can both , compression and expansion , decrease the pressure ? One should yield results opposite to the other. Where is the fault in above argument? Please help.
why people cheat infidelity signs how many people cheat
hillcrest abortion clinic stories of abortion live abortion video
the best android phone link phone tracking apps
internet drug coupons coupons for prescription medications prescription coupon
best android spy spy on mobile how to spy on an android phone
buy sildenafil 100mg viagra without a doctor prescription viagra 100 mg
buy sildenafil 100mg viagra without a doctor prescription viagra 100 mg
diprolene go furosemide 40mg
levitra pill imitrex 25mg tadalafil pill
free online coupons pharmacy coupon new prescription coupons
imitrex 50mg thepoliticalsword.com flagyl 200mg
prescription drugs discount cards link coupons for viagra printable
viagra coupons from manufacturer liberitutti.info drug discount coupons
viagra coupons free read drug coupons
pfizer coupons for viagra prescription coupon viagra discounts coupons
coupons prescriptions prescription savings cards manufacturer coupons for prescription drugs
can i take minocycline with birth control can i take minocycline with birth control can i take minocycline with birth control
cialis dosage and cialis dose for copd pts
diabetes affect sexuality cialis dosage information diabetes sexuality treatment
acheter viagra pas acheter viagra pas acheter viagra pas
where buy viagra online side effects from viagra use online viagra buy
where buy viagra online http://viagraforsaleuk1.com online viagra buy
cialis manufacturer coupon link prescription drug coupons
cialis coupon lilly coupons for cialis printable transfer prescription coupon
claritinekombo warpedfish.co.uk claritine za psa
naproxennatrium zygonie.com naproxen migraine
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
champix alkohol go champix
fusidinezuur kopen go fusidic acid
fusidinezuur kopen blog.jp-sa.org fusidic acid
cialis thepoliticalsword.com cialis walgreen coupon
cialis open cialis walgreen coupon
cefdinir red stool ski-club-auringen.de cefdinir nedir

- Saurabh (age 25)
India
A:
nice question.

I find it easiest to grasp the Bernoulli principle by thinking of the opposite direction of causation. It also helps to think initially of a nearly incompressible fluid (a liquid) rather than a gas, just to simplify things at first.

What makes something speed up? It must be acted on by an external force. What are the external forces on the flowing fluid? The most interesting ones are the pressures from the fluid behind it and in front of it, since those act where the fluid is moving and hence can do work on it. In a region where the fluid is speeding up, the pressure in front must be lower than the pressure behind. Then when it's slowing down the reverse is true. So the pressure is lowest just where the fluid is flowing fastest. The expansion or contraction of a highly compressible fluid (a gas) is a further complication, but not the core of the Bernoulli effect.

On the link you gave, the words "stretch out" are ambiguous. In your example of air flowing into a valley, someone might also say the air column stretches out, since it gets longer, although also narrower.

Mike W.
the best android phone mealmixer.com phone tracking apps
married woman looking to cheat My wife cheated on me most women cheat
abortion pill clinics abortion pill prices for abortions
married cheaters redsoctober.com dating for married men
viagra coupons from manufacturer liberitutti.info drug discount coupons
prescription drugs coupons click viagra coupon card
coupons for prescriptions click prescription drugs discount cards
viagra coupons free softballspa.com drug coupons
diabetes affect sexuality diabetes sexuality treatment
where buy viagra online side effects from viagra use online viagra buy
where buy viagra online http://viagraforsaleuk1.com online viagra buy
cialis price online lipseysguns.com cialis price history
prescription drug coupons prescription discount coupon drug coupon
cialis coupon card eblogin.com cialis coupons from manufacturer
drug discount coupons link discount coupons for prescriptions
claritinekombo warpedfish.co.uk claritine za psa
augmentin générique arbot.cz augmentin sirop
niacine movidafm.net niacin v hrani
flibanserin online lasertech.com flibanserin buy
buscopan hund go buscopan dragees
cefdinir red stool ski-club-auringen.de cefdinir nedir
lasix injetavel lasix lasix
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
singulair 4 mg granulat scottdangelo.com singulair patient information
singulair 4 mg granulat site singulair patient information
trental cena trenitalia trental nuspojave

(published on 07/03/2011)

Follow-Up #4: Bernoulli and airplanes

Q:
Bernoulli's principle states that air travels faster over the longer top of an airplane wing than under it. This assumes air takes the same amount of time to travel either side of the wing. But why is this the case? Couldn't the air above the wing just take longer to pass it thus maintaining constant velocity on either side?
cheater click wifes who cheat
hillcrest abortion clinic stories of abortion live abortion video
cvs discount card cvs coupon online prescription drugs discount cards
buy sildenafil 100mg buy sildenafil 100mg viagra 100 mg
levaquin pill diprolene 0.05% furosemide pill
free online coupons onlineseoanalyzer.com new prescription coupons
prescriptions coupons markthrice.com discount coupon for viagra
prescriptions coupons go discount coupon for viagra
viagra coupons from manufacturer open drug discount coupons
prescription drugs coupons viagra manufacturer coupon 2016 viagra coupon card
viagra coupons free link drug coupons
prescription discount coupons free prescription drug cards viagra discount coupons online
1 wk pregnant abortion pill article on abortion
viagra bestellen online viagra online shop pillen kopen
viagra bestellen online viagra pillen kruidvat pillen kopen
cialis price online lipseysguns.com cialis price history
prescription drug coupons prescription discount coupon drug coupon
prescription drug coupons prescription discount coupon drug coupon
augmentin générique arbot.cz augmentin sirop
arcoxia 30 go arcoxia wiki
champix alkohol go champix
niacine movidafm.net niacin v hrani
kamagra wikipedia click kamagra shop
cialis thepoliticalsword.com cialis walgreen coupon
motilium enceinte blog.cr-inside.org motilium et grossesse
prescriptions coupons cialis coupon drug prescription card
vivitrol alcohol naltrexone alcoholism medication narcan challenge

- Tim (age 17)
London
A:

It's not the Bernoulli principle that says that the air flows faster on the top of the curved wing. The Bernoulli principle just says that if the air flows faster on top, then the pressure on top will be lower.

You're right that the usual argument about why the air flows faster on the curved side is bogus. There's no requirement for the time of the flows on each side to be the same. The real argument is more compluicated- and I don't know it. One of the links above describes it.

Mike W.

cheater read wifes who cheat
hillcrest abortion clinic stories of abortion live abortion video
married woman looking to cheat go most women cheat
types of abortions the weeks of pregnancy what happens when you get an abortion
cvs discount card cvs coupon online prescription drugs discount cards
walgreens coupons deals blog.mrwade.co.uk walgreens photo print coupons
coupons rx prostudiousa.com www.januvia.com coupons
imitrex 50mg thepoliticalsword.com flagyl 200mg
new prescription coupon viagra coupons printable prescription coupon card
prescription drugs coupons go viagra coupon card
viagra coupons free softballspa.com drug coupons
coupon for viagra viagra trial coupon viagra discount coupons online
can i take antabuse and naltrexone can i take antabuse and naltrexone can i take antabuse and naltrexone
lisinopril and energy drinks lisinopril and energy drinks lisinopril and energy drinks
viagra bestellen online viagra pillen kruidvat pillen kopen
where buy viagra online side effects from viagra use online viagra buy
cialis price online lipseysguns.com cialis price history
drug discount coupons link discount coupons for prescriptions
venlafaxine gewichtstoename read venlafaxine fk
augmentin générique arbot.cz augmentin sirop
naprosyn roche naprosyn wiki naprosyn nedir
champix alkohol click champix
cialis open cialis walgreen coupon
renovacija stanovanja blog.myexpensesonline.co.uk renova g
vivitrol alcohol vivitrol implant narcan challenge

(published on 09/11/2014)

Follow-up on this answer.