- Bernoulli's Principle states that the air pressure is lower where the air is moving faster, such as over the top of an airplane wing. This lower pressure provides lift, allowing planes and birds to fly. - The document uses diagrams and examples like a standing tennis ball to illustrate how Bernoulli's Principle works in practice by creating differences in air pressure. It explains that the faster moving air over the top of a wing results in lower pressure than under the wing, providing the upward lift necessary for flight.

1. Bernoulli’s PrincipleBernoulli’s Principle
Created by:Created by:
Keith P. MurphyKeith P. Murphy
Winston Churchill High SchoolWinston Churchill High School
Potomac, MDPotomac, MD

2. Bernoulli’s Principle:Bernoulli’s Principle:
• A Swiss
scientist born
in 1700’s that
is most
famous for his
work in fluid
pressure.

3. Remember!!!Remember!!!
• Air is a gas and a fluidAir is a gas and a fluid
• Air pressure is due to theAir pressure is due to the
motion of its particlesmotion of its particles
• ex. The quicker a streamex. The quicker a stream
of particles travel,of particles travel,
the ???????the ???????

4. Bernoulli’s PrincipleBernoulli’s Principle
• Pressure in a moving stream
exerts less pressure than the
air surrounding the moving
stream Quick stream = low air pressureQuick stream = low air pressure
Slow stream = High air pressureSlow stream = High air pressure

5. Standing Tennis BallStanding Tennis Ball
• In your notes,In your notes,
hypothesizehypothesize
why the tenniswhy the tennis
ball ‘stands’ inball ‘stands’ in
the air.the air.
• Draw the airDraw the air
currents.currents.
PennPenn
AIR FLOWAIR FLOW

6. The AnswerThe Answer
The tennis ball is surrounded byThe tennis ball is surrounded by
an air stream of equal speed,an air stream of equal speed,
thus equal pressure.thus equal pressure.
The down force is ‘G.’The down force is ‘G.’
Thus, the ball stands onThus, the ball stands on
air. The air pressure belowair. The air pressure below
is equal with the ‘G’ force.is equal with the ‘G’ force. AIR FLOWAIR FLOW
‘‘G’G’

7. Bernoulli & FlightBernoulli & Flight
• Bernoulli’sBernoulli’s
Principle is whatPrinciple is what
allows birds andallows birds and
planes to fly.planes to fly.
• The secretThe secret
behind flight isbehind flight is
‘under the‘under the
wings.’wings.’

8. •The air on top of the wing must travel a longerThe air on top of the wing must travel a longer
distance than the air below the wing. But, air ondistance than the air below the wing. But, air on
both sides must reach the end of the wing at theboth sides must reach the end of the wing at the
same time. Therefore, the air on top of the wingsame time. Therefore, the air on top of the wing
traveling faster =traveling faster = less air pressureless air pressure..
Creates LiftCreates Lift
AIRAIR

9. Below is a NASA illustration of whatBelow is a NASA illustration of what
surface pressure is exerted on whatsurface pressure is exerted on what
surface areas of the wing. Is thissurface areas of the wing. Is this
plane ascending or descending?plane ascending or descending?

10. This diagram shows regions of airThis diagram shows regions of air
pressure around specific areas of thepressure around specific areas of the
wing. Again, notice that the low pressurewing. Again, notice that the low pressure
region is above the wing, allowing forregion is above the wing, allowing for
upward thrust.upward thrust.

11. LIFTLIFT
GRAVITYGRAVITY
THRUSTTHRUST
DRAGDRAG

12. •The engines provideThe engines provide THRUST.THRUST.
•The wings provideThe wings provide LIFT.LIFT.
•Gravity provides theGravity provides the ‘G force.’‘G force.’
•And, fluid friction provides theAnd, fluid friction provides the
DRAG.DRAG.
•What is happeningWhat is happening
if the airplane isif the airplane is
flying at constantflying at constant
altitude?altitude?
What forces are =?What forces are =?