Shock Waves: a Jet Aircraft, in Level Flight at Constant

Multiple Choice

Shock waves: A jet aircraft, in level flight at constant speed, is observed directly overhead. A sonic boom is heard later, at which time the line of sight to the aircraft forms a 56° angle with respect to the horizontal. The speed of sound is 325 m/s. What is the Mach number (the ratio of the speed of the jet to the speed of sound) for the aircraft?

A) 1.2
B) 1.8
C) 1.9
D) 2.1
E) 2.2