Question

an automobile horn emits a sound frequency of 800 hzas measured by a stationary observer. what frequency would be measured by an observer moving toward the source at 35:0 m

Answer 1

The source emits sound at 800 / sec - f = 800 / s

The auto moves at 35 / 800 sec (the apparent wavelength is shortened)

f' = f + f vo / v where vo is the speed of the observer

f' = f (v + vo) / v rewriting the above equation

f' = 800 / sec (331 + 35) / 331 using 331 m/s as the speed of sound

f' = 885 / sec sound heard