Drag is reduced by a plane's smooth shape. What is another factor that reduces drag in construction?

Drag is reduced by a plane's smooth shape. What is another factor that reduces drag in construction?

• A. Increased engine power
• B. A plane's smooth shape
• C. Higher altitude
• D. Decreased wing area

Answer: (B)

Drag rises with the amount of air the plane has to push aside, which depends on air density. At higher altitudes the air is thinner, so there are fewer molecules hitting the aircraft at the same speed. That means less resistance and lower drag for the same flight speed. This is why cruise at high altitude helps keep drag down, even if the plane’s smooth shape already reduces drag. Other choices don’t fit as cleanly: increasing engine power boosts thrust, not drag; a smooth shape is already accounted for as a drag-reducing factor; lowering wing area can reduce drag in some cases but also reduces lift and overall performance, so it isn’t a straightforward way to lower drag.

Drag rises with the amount of air the plane has to push aside, which depends on air density. At higher altitudes the air is thinner, so there are fewer molecules hitting the aircraft at the same speed. That means less resistance and lower drag for the same flight speed. This is why cruise at high altitude helps keep drag down, even if the plane’s smooth shape already reduces drag.

Other choices don’t fit as cleanly: increasing engine power boosts thrust, not drag; a smooth shape is already accounted for as a drag-reducing factor; lowering wing area can reduce drag in some cases but also reduces lift and overall performance, so it isn’t a straightforward way to lower drag.