A plane flies horizontally at Mach 1.2, and an observer on the ground hears the sonic boom 15 seconds after the plane passes a point directly overhead. What is the altitude of the plane? [Hint: Usound = 343 m/s.]

Cemile is flying a jet plane at Mach 2.5 at an altitude of 1500m. She flies past her students who are standing at ground level. How much time passes before the students hear the sonic boom after the plane flies directly overhead? Assume that the speed of sound in air is 330m/s.

Two strings both vibrate at exactly 802 Hz. The tension in one of them is then increased slightly. As a result, 3 beats per second are heard when both strings vibrate. What is the new frequency of the string that was tightened?  Calculate to one decimal.

What frequency of sound is observed if the 444 Hz source is traveling away from a stationary observer at a speed of 30.2 m/s? (assume the speed of sound in air is 343 m/s)