2. Bernoulli’s Principle Created by: Keith P. Murphy Winston Churchill High School Potomac, MD

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

4. Remember!!! Air is a gas and a fluidAir is a gas and a fluid Air pressure is due to the motion of its particlesAir pressure is due to the motion of its particles ex. The quicker a stream of particles travel, the ???????ex. The quicker a stream of particles travel, the ???????

5. Bernoulli’s Principle Pressure in a moving stream exerts less pressure than the air surrounding the moving stream Quick stream = low air pressure Slow stream = High air pressure

6. Standing Tennis Ball In your notes, hypothesize why the tennis ball ‘stands’ in the air.In your notes, hypothesize why the tennis ball ‘stands’ in the air. Draw the air currents.Draw the air currents. Penn AIR FLOW

7. The Answer The tennis ball is surrounded by an air stream of equal speed, thus equal pressure.The tennis ball is surrounded by an air stream of equal speed, 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 FLOW ‘G’

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

9. 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 on both sides must reach the end of the wing at the same time. Therefore, the air on top of the wing traveling faster = less air pressure. Creates Lift AIR

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

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

12. LIFT GRAVITY THRUST DRAG

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