On a RADAR screen an operator spots some kind of aircraft, flying 1200 feet per second at an altitude of 14 kilometres. What flight regime is this aircraft in?

Question

Subsonic, Transonic, supersonic, Hypersonic

Answer 1

To determine the flight regime of the aircraft, we need to compare its speed to the speed of sound at that altitude.

At sea level, the speed of sound is approximately 1,125 feet per second. However, at higher altitudes, where this aircraft is flying, the speed of sound decreases.

To find the speed of sound at an altitude of 14 kilometers (which is approximately 45,931 feet), we can use the equation:

Speed of sound (feet per second) = 1,125 feet per second * √(altitude in feet/ sea level altitude in feet)

Speed of sound = 1,125 feet per second * √(45,931 feet/ 0 feet)
Speed of sound ≈ 1,125 feet per second * √(45,931)
Speed of sound ≈ 1,125 feet per second * 214.19
Speed of sound ≈ 240,976 feet per second

Now, we can compare the speed of the aircraft (1200 feet per second) with the speed of sound (240,976 feet per second) at that altitude.

Since the aircraft's speed (1200 feet per second) is less than the speed of sound (240,976 feet per second), we can conclude that the aircraft is in the subsonic flight regime.