Question

What is not an aspect of relative wind?

A:Speed
B:Direction
C:Air movement
D:Wind tunnel

Answer 1

I would say that wind has all of those except for one... Finish the sentence.

"I've never met a wind that had (a) _________________ ."

Answer 2

I would say "speed". Because a relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil.

Answer 3

@Bella♥ It isn't just the direction of movement, right? Is it also the velocity or speed of the movement?

"In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil."
"...but at a great distance from the aircraft or airfoil the movement of the air can be represented by a single vector."
"The relative wind is of great importance to pilots because exceeding the critical angle of attack will result in a stall, regardless of airspeed."
"Relative wind is also used to describe the airflow relative to an object in freefall through an atmosphere..."
http://en.wikipedia.org/wiki/Relative_wind

"Relative wind is defined as the airflow relative to an airfoil."
http://www.dynamicflight.com/aerodynamics/relative_wind/

"The relative wind, therefore, is the airflow produced by the aircraft moving through the air. The relative wind is in a direction parallel with and opposite to the direction of flight."
http://www.allstar.fiu.edu/aero/flight33.htm

I'm not familiar with this material, but two links seem to have dissenting opinions. Wikipedia's link states that it \(\sf is\) direction, and can be expressed by a vector, but that might be for just direction. It also states that, in at least one situation, angle matters more than wind speed. Which means that maybe they developed a concept of just the relative wind's direction and called it "relative wind." But, intuitively and according to the other two links, it seems like it is the relative motion between the air and the airfoil or other object. The last quote from Wikipedia describes just that, so, I think speed might be considerable.

I consider Wikipedia to be very reliable for high traffic articles because some experts like to preserve the truth (and maybe their ego, haha). This is a smaller article, and I'm not knowledgeable in all the related fields to verify the accuracy of any statements on the concept.