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Next: Chapter 20: Problem 59 Up: Waves and Optics, Solutions Previous: Chapter 20: Problem 55

Chapter 20: Problem 56

Question:        An ambulance emitting a whine at $\nu_1 = 1.602 \ {\rm kHz}$overtakes and passes cyclist pedaling a bike at $v_2=2.63\ {\rm m/s}$. After being passed, the cyclist hears a frequency of $\nu_2 = 1.590 \ {\rm kHz}$. How fast is the ambulance moving?

Solution:         Again we have the source and the observer moving in the same direction, and so we have

$\displaystyle \nu_2$ = $\displaystyle \nu_1\left( { c+v_2\over c+v_1}\right)$  
v1 = $\displaystyle {\nu_1\over\nu_2} (c+v_2) - c \ =\ 5.24\ {\rm m/s}
\ \ .$ (12)



Martin Savage
1999-01-21