a. A fire engine is moving at 40 m/s and sounding its horns. A car in front of the fire engine is moving at 30 m/s, and a van in front of the car is stationary. Which observer hears the fire engine's horn at higher pitch, the driver of the car or the van?
b. A bat flying toward a wall emits a chirp at 40 kHz. Is the frequency of the echo received by the bat greater than, less than, or equal to 40 kHz? Explain.
c. Two tuning forks are struck. One at 748 Hz and the other at 234 Hz. Which wavelength travels faster? (this one is actually reworded differently, I didn't write down the problem, but it was something along these lines...)
wavelength = 4L
I don't think any are required for these?
The Attempt at a Solution
Well I know that the closer the wavelengths are, the higher the pitch is. However, for (a), there are two moving objects, which throw me off.
And for (b), since the bat is still moving towards the wall, does that have any effect?
As for (c), would they both travel at the same speed (speed of sound)?