Crave the Wave!!

[Phenylethylamine]

Oh, speaking of the Doppler effect, it is nearly always described incorrectly. I have heard so many different sources say (paraphrased) "As the vehicle moves toward you, the apparent frequency of the noise increases, and as it moves away from you, the apparent frequency decreases."
This is false.
Actually, as the vehicle moves toward you, the apparent frequency of the noise is greater than its actual frequency, but it decreases as the vehicle approaches you. When the vehicle is level with you, the apparent frequency is the same as the actual frequency, and once it passes you, the apparent frequency continues to decrease.

[Uranium235]

Most event answer keys have the former down as the answer though, so you would get it wrong even if you are right.

[Phenylethylamine]

I don't know about other people, but in my mind it would be worth it to be marked wrong just to know you were actually right. I would hate the idea that I'd dumbed down my answer so the event sup who had it WRONG could look at my paper and check it off as right. If the sup is stupid (or just unobservant), it's not my fault, and I wouldn't stoop to putting a wrong answer just because it might be what they want.

[hbk.showstopper]

......Interesting.........I guess that makes some sense if you put it that way although.........

[49ersfan]

One of these times, I'm making a full-fledged test for crave the wave.

[EastStroudsburg13]

What if you make your answer so that it is clear what the exact circumstances are? If you explain it the way you did in your post, the supervisor may have to mark it right.

[Mr. Cool]

Oh, speaking of the Doppler effect, it is nearly always described incorrectly. I have heard so many different sources say (paraphrased) "As the vehicle moves toward you, the apparent frequency of the noise increases, and as it moves away from you, the apparent frequency decreases."
This is false.
Actually, as the vehicle moves toward you, the apparent frequency of the noise is greater than its actual frequency, but it decreases as the vehicle approaches you. When the vehicle is level with you, the apparent frequency is the same as the actual frequency, and once it passes you, the apparent frequency continues to decrease.

Uh, actually that makes no sense whatsoever.

[chia]

i agree wholeheartedly. that totally doesn't make sense.

[Phenylethylamine]

It's not very helpful to me if you just say that doesn't make sense... specifically what doesn't make sense?

What if you make your answer so that it is clear what the exact circumstances are? If you explain it the way you did in your post, the supervisor may have to mark it right.

Usually, the people grading the tests are just working off an answer sheet and may or may not actually know anything about the topic. If your answer doesn't substantially match what it says on the key, it gets marked wrong.

I think that maybe stating it this way might make it a little clearer: while the vehicle is approaching you, the apparent frequency of the noise is greater than the actual frequency. As it approaches, the apparent frequency decreases until it reaches the actual frequency- at the exact point that it passes you- and then continues to decrease past that frequency. The decrease in frequency is consistent (I was going to say linear, but then I realized that I'm not sure it's linear- but in any case, a graph of the apparent frequency over time as it approaches, passes, and then moves away from you has a continuous negative slope and can be defined with one function).

[kjhsscioly]

so then the apparent frequency is greater when the vehicle is approaching you, it is just that the difference between the actual and apparent frequencies is getting less?

on a test question, they would usually ask what the Doppler effect is, not how it changes, so that is unlikely to be a question anyway

It is all in the wording of the question, the supervisor may be trying to trick unwary teams into saying that the frequency goes up ... or they may just be ignorant