Dynamic Lift Force on an Aircraft Using Bernoulli's Principle - Physics Problems

This physics video tutorial provides a basic introduction into how a dynamic lift force can be generated on an aircraft by understanding a few concepts from Bernoulli's principle. It explains how to derive the formula to calculate the lift force using bernoulli's equation. As the airplane moves through air, air flows faster on the top surface of the wing creating a low pressure region. The pressure on the bottom surface is higher due to a low air speed. This creates an upward lift force that depends on the density of the air, the area of the wings, and the square difference between the wind speed above and below the plane's wings. This video contains plenty of examples and practice problems on how to calculate the dynamic lift force on an airplane wing using bernoulli's principle.

Fractional Volume of Submerged Object:

Hydrometer Physics Problems:

Volume Flow Rate and Mass Flow Rate:

Equation of Continuity:

Bernoulli's Equation:

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Torricelli's Theorem & Speed of Efflux:

Venturi Meter Problems:

Dynamic Lift Force:

Viscosity of Fluids and Velocity Gradient:

Poiseuille's Law:

Surface Tension of Water:

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Fluid Pressure Review:

Simple Harmonic Motion:

The Simple Pendulum:

Full-Length Videos and Worksheets:

Physics PDF Worksheets:

[kyugreywolf]

What an absolutely amazing video. I'm in the third year of my degree now, and was a little confused with the direction of lift. This helped so, so much. Thanks a lot!

[solidkreate]

Thank You, this is EXACTLY the stuff I wanted to know.

[warrenchu]

Lift: Because the air moves faster over the top of the wing, it is less dense (more spread out). Less dense air means lower air pressure.
The air pressure difference between the top and bottom of the wing is what causes the lift.
This is the principle behind Bernoulli's Equation, which says the energy in the air between its pressure (the outward expanding force of a parcel of air and a form of energy density) and its kinetic energy (as given by the v squared terms) are conserved.
What causes a decrease in lift by ice buildup on wings?
The drag on the air causes it to slow down, negating the pressure difference.
Moreover, it causes turbulence at the trailing edge of the wing due to less airflow over the top of the wing.

[AlexOvechkinMVP]

before this video blows, just wanted to say thanks for these videos. love you my man!

[johng]

Nurse here. Bad at math. Love math anyway. Love your channel. subbed.

[tomatrix]

All your videos are really great. Please continue to make them

[Grizzlybearsaremyfavoritebears]

thank you good sir this actually helped a bunch

[AboOmar]

Why it takes me so long to find this YouTube Channel... Great video my freind.

[nidaljodeh]

At 6:22 you state the "wind has to travel a greater distance at the top part...it speeds up." This is incorrect. The flow of air over the top of the wing is created by squeezing the streamlines together over the wing. The conservation of mass and the continuity equation state that the mass flow rate into and out of a stream tube of streamlines has to speed up as area between the streamlines is reduced. Or, if you'd like to prove it to yourself, put your thumb over the end of a garden hose...area is reduced and velocity is increased. m_dot1 = m_dot2, or entry density x entry area x entry velocity = exit density x exit area x exit velocity.

[paulofernandes]

Fabulous! yr the man! Nice 2 meet u! Pls, never stop, we need u! God bless u!

[anshusinghal]

Sir i have a doubt, that we can use Bernoulli theorem in any point of a single streamline
But you used Bernoulli equation in two different streamline. Why??

[NitinThulkarUK]

Thank you so much for explaining the lift force and validation using basic equation. Could, you please advice if same can applied under water cases. I would like to know, if same physics fundamentals can be applied for underwater scenario.

[БерикМирза]

Hello. Why you don’t use lift coefficient?

[FlywithMagnar]

I like your videos about chemistry, but in this video, you get things wrong.

In example 1, you say that low pressure is formed over the top of the house. How? A lower pressure means the velocity of the air over the roof top must increase. Bernoulli's principle does not say "when the velocity is high, the pressure is low" and vice versa. Bernoulli's principle says when the velocity of an airflow changes, the static pressure changes in accordance with Bernoulli's equation. Therefore, you cannot use Bernoulli's equation to compare the airflow outside and inside a house with walls. You must compare the velocity of the air ahead of the house with the velocity of the air over the roof. With a flat roof, the lifting force will be very low.

In example 2, you describe lift in accorance with the "equal transit" hypothesis. Sadly, this idea is taught to student pilots all over the world, but it is not correct. Think about it: How can an air molecule that was separated from another air molecule by the wing know when the other air molecule will reach the trailing edge of the wing? Wind tunnel tests show that the air flowing over the wing reaches the trailing edge before the air flowing under the wing. If you search for "Prof. Holger Babinsky" and "Lift" you will see how it works.
Your drawing shows a wing with a flat undersurface and zero angle of attack. Therefore, the velocity of the air under the wing will have the same as the velocity of the airplane, and the static air pressure under the wing is the same as the static pressure in the atmosphere. To get a higher static pressure under the wing, the wing must meet the airflow with an angle, called the angle of attack. And don't forget when a wing produces lift, it deflects air downwards in accordance with Newton't third law of motion.

For a better understanding of Bernoulli's equation, I recommend the channel of The Efficient Engineer.

[dominicmutzhas]

What exactly are the assumption we use to apply the Bernoulli equation?

[danielgrimes]

Thanks for the video man. Really appreciate it, but I was wondering why g @ 9:55 is 9.8 sorry 😅 new to physics

[bonganesithole]

thanks a lot sir....can you please add a few changeling like pitot-tubes

[Duck-jcox]

Thanks! How do I work out velocity of air over and under the wings?

[mohammedthalha]

Sir in question no.2 there are 2 wings but you calculated only one wing

[pipacs]

How do you get your result in Newton at the first calculation, if your dimensions are: 1/2*[m/s]^2*[m^2]*[kg/m^3 ]?