Question

How is the zero-lift drag force related to atmospheric pressure?

(a) The zero-lift drag force is directly proportional to atmospheric pressure

(b) The zero-lift drag force is indirectly proportional to atmospheric pressure

(c) The zero-lift drag force is twice multiple to atmospheric pressure

(d) The zero-lift drag force is half divided to atmospheric pressure

I got this question during an online exam.

The origin of the question is Drag Force topic in section Aircraft Force Systems and the Equations of Motion of Aircraft Performance

Answer 1

Right answer is (a) The zero-lift drag force is directly proportional to atmospheric pressure

To elaborate: The zero-lift drag force is directly proportional to atmospheric pressure i.e. the zero-lift drag force increases as the increase in atmospheric pressure. This is because the drag force is directly proportional to the dynamic pressure.