To measure her speed, a skydiver carries a buzzer emitting a steady tone at 2500 Hz. Assume the air is calm and the speed of sound is independent of altitude. While the skydiver falls at terminal speed, her friend on the ground receives waves of frequency 2750 Hz.
A. If the skydiver hears the sound of the buzzer reflected from the ground together with her own buzzer's sound, what beat frequency does she hear?