A woman stands at rest in front of a large, smooth wall. She holds a vibrating tuning fork of frequency 10 directly in front of her (between her and the wall).
(a) The woman now runs toward the wall with speed Uw. She detects beats due to their interference between the sound waves reaching her directly from the fork and those reaching her after being reflected from the wall. How many beats per second will she detect? (Note: If the beat frequency is too large, the woman may have to use some instrumentation other than her ears to detect and count the beats.)
(b) If the woman instead runs away from the wall, holding the tuning fork at her back so it is between her and the wall, how many beats per second will she detect?