1. Two sources, A and B, emit a sound of a certain wavelength. The sound emitted from both sources is detected at a point away from the sources. The sound from source A is a distance d from the observation point, whereas the sound from source B has to travel a distance of 3λ. What is the largest value of the wavelength, in terms of d, for the maximum sound intensity to be detected at the observation point? If d = 10.0 m and the speed of sound is 340. m/s, what is the frequency of the emitted sound?

2. A train whistle emits a sound at a frequency f = 3000. Hz when stationary. You are standing near the tracks when the train goes by at a speed of v = 30.0 m/s. What is the magnitude of the change in the frequency (|Δf|) of the whistle as the train passes? (Assume that the speed of sound is v = 343 m/s.)

3. Two trains are traveling toward each other in still air at 25.0 m/s relative to the ground. One train is blowing a whistle at 300. Hz. Assume that the speed of sound is 343 m/s.

a) What frequency is heard by a man on the ground facing the whistle-blowing train?

b) What frequency is heard by a man on the other train?