# Aerodynamics Questions and Answers – Downwash and Induced Drag – 3

This set of Aerodynamics Quiz focuses on “Downwash and Induced Drag – 3”.

1. Is down wash is change in direction of lift?
a) True
b) False

Explanation: Down wash is the change in direction of air deflected by the aerodynamic action of an airfoil, wing, or helicopter rotor blade in motion, as part of the process of producing lift. When the relative wind moves from nose to down side of the wing which causes change in direction of air and produce lift.

2. Is Newton’s third law of motion is an application for lift on airfoil?
a) False
b) True

Explanation: Lift on airfoil is an example of the application of Newton’s third law of motion. The force required to create the downwash is equal in magnitude and opposite in direction to the lift force on the airfoil.

3. Is air pressure on the top of the wing is lower than the pressure below the wing?
a) True
b) False

Explanation: For a lifting wing, the air pressure on the top of the wing is lower than the pressure below the wing. The tip of the wing, the air is free to move from the region of high pressure into the region of low pressure. The resulting flow at the left by the two circular blue lines with the arrowheads of flow direction.

4. Is vortex lines leading from the wing tips?
a) False
b) True

Explanation: Vortex lines leading from the wing tips, if the atmosphere has very high humidity, you can sometimes see the vortex lines on an aircraft during landing as long thin clouds leaving the wing tips which causes the down wash in the lower surface of the wing.

5. Is wing tips vortices produce the down wash?
a) True
b) False

Explanation: The wing tip vortices produce a downwash of air behind the wing which is very strong near the wing tips and decrease toward the wing root. The effective angle of attack of the wing is decreased by the downwash.
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6. Is induced drag produce lift?
a) True
b) False

Explanation: In aerodynamics induced drag will produce lift. It is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift.

7. Is a higher aspect ratio flat plates has a higher lift?
a) True
b) False

Explanation: The higher aspect ratio flat plates had higher lift and lower drag, a plane of fixed size and weight would need less propulsive power the faster it flew, the counter-intuitive effect of induced drag will produce on the wing.

8. Is induced drag is related to the amount of induced downwash?
a) True
b) False

Explanation: Induced drag is related to the amount of induced downwash in the vicinity of the wing. The grey vertical line labeled L is perpendicular to the free stream and indicates the orientation of the lift on the wing.

9. Is lift and drag are the total aerodynamic force acting the body?
a) True
b) False

Explanation: The total aerodynamic force acting on a body is usually thought of as having two component of force parallel to the oncoming flow is called drag and the component perpendicular to the oncoming flow is called lift.

10. Is lift is produced by the changing direction of the flow?
a) False
b) True

Explanation: Lift is produced by the changing direction of the flow around a wing. The change of direction results in a change of velocity, which is an acceleration, to charge the direction of flow requires that a force is applied to the fluid acting on the wing.

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