What does jet propulsion refer to?

• A. The action produced by the ejection of air, another gas, or liquid
• B. The thrust produced by propeller-driven engines
• C. The resistance encountered by an aircraft in flight
• D. A method of landing an aircraft

Answer: (A)

Jet propulsion is thrust produced by accelerating and expelling a working fluid (air, another gas, or liquid) rearward through a nozzle. When a mass is ejected backward, Newton’s third law gives an equal and opposite forward force on the aircraft, pushing it ahead. This description matches how jet engines generate forward motion by creating a high-speed exhaust jet.

Propeller-driven thrust, while it still moves air, relies on rotating blades to push air and isn’t defined by ejecting a high-velocity jet, so it’s a different propulsion mechanism. The other options describe drag or landing methods, which aren’t about how propulsion works.