By: Devin Zenner & Grace Overend Hovercraft By: Devin Zenner & Grace Overend
Picture of our Hovercraft!
Actual Plans
Pressure Pressure P=F/A Pressure under hovercraft has to be more than 14.7 psi. PSI Pounds per square inch of pressure “normal” psi is 14.7, what we’re used to everyday As you increase by 10,000 ft. you subtract 4 psi from normal…pressure decreases by altitude. Estimate the amount of psi that we will need Take weight that we want to lift divided by the surface area (of hovercraft).
Bernoulli’s Principle P+1/2P2+Pgh=C As the Velocity of a fluid increases the Pressure exerted by the fluid decreases. Applies to leafblower and holes in plastic… http://library.thinkquest.org/27948/bernoulli.html
Fluid Mechanics Examples in everyday life Airplane Army Hovercrafts Wings Lift/takeoff Landings Army Hovercrafts HUGE Holds 12 Hummers Water AND Land
Fluid Mechanics/Lift Lift Molecules provide the necessary lift. The more molecules that are present the more pressure is built up providing more lift.
Pascal’s Principle Pascal’s Principle Fluid (air) in a closed container is transmitted equally to every point of the fluid and to the walls of the container. Plastic skirt that contains the air provides the necessary lift for the hovercraft. Air is equally pushed out of all the holes in the bottom Lifts the hovercraft off of the ground.
Pascal’s Principle Continued Necessary for the pressure to be equal throughout the skirt Prevent uneven lift. Pressure is equal to the initial force divided by the initial area Also equal to the final force divided by the final area. P =F1/A1=F2/A2
Example of Pascal’s Principle The small piston of a hydraulic lift has an area of 0.20m2. A car weighing 1.20x104N sits on a rack mounted on the large piston. The large piston has an area of 0.90m2. How large a force must be applied to the small piston to support the car? Given: A1=0.20m2 A2=0.90m2 F2=1.20x104 N Unknown: F1=? Use the equation for pressure and apply Pascal’s principle.
Pascal’s Answer F1=(A1/A2)F2 =(0.20m2/0.90m2)(1.20x104 N) F1=2.7x103 N
Pictures! Weeeeee!
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