Answer :
The magnitude of the airplane's angular momentum relative to a ground observer directly below is approximately 42,578,452 kg·m²/s, calculated using the formula L = r * m * v.
To determine the magnitude of the airplane's angular momentum relative to a ground observer directly below the airplane, we can use the formula for angular momentum L which is given by
L = r * m * v,
where r is the radius (which, in this case, is the altitude of the airplane), m is the mass of the airplane, and v is the velocity of the airplane.
So, for an airplane of mass 12939 kg flying at an altitude of 19 km (which is 19000 m when converted to meters) with a constant speed of 172 m/s, the angular momentum can be calculated as follows:
L = r * m * v
L = 19000 m * 12939 kg * 172 m/s
L = magnitude of angular momentum
Performing the multiplication, we obtain:
L = 42,578,452 kg·m²/s
Hence, the magnitude of the airplane's angular momentum relative to a ground observer directly below is approximately 42,578,452 kg·m²/s.