Crave the Wave helpppppppp

[wlsguy]

On the Northmont test, #8 and #12 use a triangle symbol (no clue what it's called) to represent some sort of difference. Number 12 is about doppler, and the fomula (from the wiki) f'=f+fv/c doesn't seem to work. Could anyone be as neighborly as to explain these to me?

The triangle is the delta symbol. It refers the difference in time for question #8 (73 sec) and the difference in speed for # 12 (30m/s).

Question number 12 is shown a little differently than the wiki formula to help explain it.
The answer starts with the wavelength if the source was not moving. =1.14m This uses only the speed of sound.343 m/s
The next computation calculates the wavelength of the 30 m/s movement = .1m

To get the final answer you need to subtract the movement effect from the stationary amount to get the wavelength that you hear of 1.04m.
You then plug the 343m/s / 1.04m to get the answer = frequency of 329.81hz.

[blue cobra]

Thanks, I understand it a lot more now. And now that you mention it, I do remember the delta from the slope formula.