1. Bernoulli’s Principle

2. What does Bernoulli’s principle state?
The pressure of a fluids flowing horizontally decreases as the speed of the fluid increases.
Only applies for steady flow
Flow follows streamlines

3. Like the work/energy theorem: if we have information like pressure, speed or height about 1 region, we can find out information about another region.

4. REGION 1
REGION 2

5. Common Applications

6. Bernoulli & Flight
Bernoulli’s Principle is what allows birds and planes to fly.
The secret behind flight is ‘under the wings.’

8. AIRFOIL On top: greater air speed and less air pressure
On bottom: less air speed and more air pressure
net force: upward

9. LIFT
THRUST
DRAG
GRAVITY

10. Bernoulli & Racecars
Spoiler provides better traction and avoids lift

11. SPOILER – airfoil reversed -
less air speed
more pressure
net force: downward
greater air speed
less pressure

12. Other Applications

13. Paper Lift What happens to the paper when you blow across the top?
Paper rises
Why?
Breath speeds air molecules which decrease pressure on top of paper
The pressure under the paper pushes the paper up

14. Inverted Umbrella
Use Bernoulli’s principle to explain why your umbrella inverts on a windy day.
Wind blows on top of umbrella
Air molecules speed up on top f umbrella; therefore, pressure decreases on top of umbrella
Air under umbrella which has greater pressure pushes up and inverts umbrella

15. Shower Curtain
Use Bernoulli’s principle to explain why your shower curtain blows inward with a hot shower.
Hot inside shower
Air molecules speed up inside shower; therefore, pressure decreases inside shower
Air outside shower with
more pressure pushes
shower curtain in