Final answer:
An increase in temperature from 25 to 50° F while maintaining a constant pressure altitude of 5,000 feet leads to an increased density altitude, which means the air behaves as if it were at a higher altitude, being less dense due to the expansion of air molecules.
Step-by-step explanation:
The effect of a temperature increase from 25 to 50° F on the density altitude if the pressure altitude remains at 5,000 feet will result in a higher density altitude. This means that, even though the physical altitude has not changed, the aerodynamic effects on an aircraft will be as if it were at a higher altitude. The air becomes less dense as temperature increases, which decreases air pressure and can affect engine and aerodynamic performance.
Changes in Density Altitude
As temperature rises, the molecules in the air move faster and spread apart, causing the air to expand. This reduces the air's density—the number of air molecules in a given volume—which is effectively simulated as a higher altitude because there are fewer oxygen molecules at higher altitudes. If we were to consult a standard altitude to air density relationship table (like Table A3 mentioned above), we would see that for a fixed pressure altitude, as temperature increases, the corresponding air density decreases, implying an increase in the equivalent density altitude.