Q1- Two loudspeakers emit 430 Hz notes. One speaker sits on the ground. The other speaker is in the back of a pickup truck. You hear 9 beats per second as the truck drives away from you. What is the truck's speed?

Q2- A balloon driven by a 35 km/h wind emits a sound of 860 Hz as it approaches a tall building (a) What is the frequency of the sound heard by an observer at the window of this building? (b) What is the frequency of the reflected sound heard by a person riding in the balloon?

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