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Air Resistance
Name: Mathías Vásconez
Date: 7-3-2013
Grade: 9th “B”
Air resistance, also called drag, is the forces that are in opposition to the relative motion of an object through the air.Drag forces act opposite to the oncoming flow velocity. Drag, unlike other resistive forces, depends directly on velocity. Drag is the component of the net aerodynamic force acting opposite to thedirection of the movement and the forces working perpendicular are called lift. Drag is overcome by thrust. In astrodynamics, atmospheric drag is both a positive and a negative force depending on thesituation. It is a drain on fuel and efficiency during lift-off and a fuel savings when a spacecraft is returning from to Earth.

Air resistance is usually calculated using the drag equation. Thisequation calculates the force experienced by an object moving through a fluid or gas at relatively large velocity. The result is called quadratic drag. Once the drag is calculated, you have to use aformula to calculate the power needed to overcome that drag in order propel and object. Power needs are the cube of the velocity, so if it takes 10 horsepower to go 80 kph it will take 80 horsepower to go160 kph. As you can see a doubling of speed requires the eight times the amount of power. Knowing this is essential in calculating the amount of fuel it will take to make a journey.
There are threemain types of drag in aerodynamics: lift induced, parasitic, and wave. Each affects an objects ability to stay aloft as well as the power and fuel needed to keep it there.
Lift induced(induced)dragoccurs as the result of the creation of lift on a three-dimensional lifting body(wing or fuselage). It has two primary components: vortex drag and lift-induced viscous drag. The vortices derive fromthe turbulent mixing of air of varying pressure on the upper and lower surfaces of the body. These are needed to create lift. As the lift increases, so does the lift-induced drag. For an aircraft this...