Engineering Questions with Answers - Multiple Choice Questions

# Aerodynamics – Downwash and Induced Drag – 3

1 - Question

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 - Question

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 - Question

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 - Question

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 - Question

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.

6 - Question

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 - Question

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 - Question

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 - Question

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