Thrust will

• A. Increase at low temperatures
• B. Increase at high temperatures
• C. Decrease at low temperatures
• D. Unchanged

Answer: (A)

Thrust comes from accelerating a mass of air through the engine, so it depends on how much air the engine can move and how much energy is imparted to it. Cooler ambient air is denser, meaning more air mass enters per second for the same intake area and engine speed. With more air available, more fuel can be burned, releasing more energy and increasing the exhaust energy and velocity relative to the inlet. That higher exhaust momentum gives greater thrust. At higher temperatures, air is less dense, so mass flow is lower and thrust tends to decrease. In short, colder air improves engine mass flow and energy addition, leading to higher thrust.