Lesson Three: How does Bernoulli’s principle work on a plane?
Return to Mini-Course: How do planes fly?
How Wings Lift the Plane
Birds use their strong breast muscles to flap their wings and give them the thrust to move throught the air and fly. In a way, birds use a swimming motion to get the lift needed to fly. Plane wings have a similar shape as bird wings, but instead of flapping their wings, we use engines to thrust them into the air and create the lift needed to fly.
Airplane wings are shaped to make air move faster over the top of the wing. When air moves faster, the pressure of the air decreases. So the pressure on the top of the wing is less than the pressure on the bottom of the wing. The difference in pressure creates a force on the wing that lifts the wing up into the air.
Other applications of Bernoulli's principle
A fast moving train
Q: Why it is dangerous to stand near a railway line when a fast train is passing by?
A: When a train is moving at a high speed, the velocity of air increases; according to bernoulli' s principle, as the velocity increases, the pressure decreases. Thus the place where we are standing is a region of high pressure and the place where the train is moving is a region of low pressure. We would be pulled from a region of high to a region of low pressure.
Two sailing boats
Q: The bernoulli effect causes passing ships to be drawn togeather when the ships are close and moving in?
A: For two boats travelling closely in the same direction, it would create a situation where the water between the two boats must travel faster than the water outside of the two boats. In this case, pressure is reduced where water is moving quickly. This would bring the two boats together.
Assignment
Could you think of other phenomena that can be explained with Bernoulli's principle in our life? Write an essay to describe the phenomenon and explain it with what you have learned in this mini-course.
References
http://pressure8f.pbworks.com/w/page/18361780/airplane%20pressure
https://www.grc.nasa.gov/www/k-12/UEET/StudentSite/dynamicsofflight.html