Paper Airplanes Rachael Lee (15). Why? Why are the airplanes able to fly after the initial thrust we...

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Paper AirplanesRachael Lee (15)

Why?• Why are the airplanes able to fly after

the initial thrust we gave them?

• How are they able to glide for so long afterwards?

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Well, …• Many different paper airplane designs

• --> Affects physics applied to it

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Factors:• Lift

• Air Drag (or Air Resistance)

• Density

• Pressure

• Thrust

Lift• Your paper airplane uses lift to carry it

through the air and to its landing area.

• How?

• Lift can only happen when in the presence of a moving fluid

• --> air has fluid properties.

Simulate it!• This can be easily simulated in everday

life. Next time you are riding in a car with someone stick your hand out the window. Have your fingers pointing in the direction of the motion of the vehicle. Now move your hand up and down slightly. You can feel the lift and drag that your hand creates.

Equation• L = lift

• Cl = lift coefficient

• (rho) = air density

• V = air velocity

• A = wing area

Air Drag• resistive force of the air pushing back.

• limits flight distance

• Too high -> trying to throw a paper airplane under water

• Equation:

Density• the amount of mass compacted into an

area of an object

• Equation: p=m/V

• helps define the air resistance

• Temperature - also a factor of density

Pressure• Like you might feel pressured to do homework• Equation: P=F/A (force ÷ area)• acts in all directions• acts on a paper airplane by exerting a force over the

airplane• separate equation that relates pressure to the parts

of a fluid such as density, depth and gravitational field strength

• P=pgh (P = pressure, p = density, g = gravitational strength, h = depth)

• Means that higher you go in the air, the less pressure there is.

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http://ambitiontofly.files.wordpress.com/2011/10/wings_flow_air2.gif

Thrust• long distance flight• lift is dependant on thrust with an airplane• If thrust = air resistance, then the object is stationary• cannot be maintained --> paper airplanes come down• related to Newton's first law: in the absence of an

external force, a body at rest remains at rest and a body in motion remains in motion

• Use Newton’s second law: F=ma (force is equal to the mass of an object multiplied by the acceleration)

References• http://www.123HelpMe.com/view.asp?id=153261

• http://paperplane.org/Aerodynamics/paero.htm

• http://blogs.bu.edu/biolocomotion/2011/10/21/the-physics-of-paper-planes/