Slowest sound wave

[samvillian]

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So there was this question in the BR that bugged me... it asked through which medium sound waves will travel the slowest.

Listed were a vacuum, water, air, and some metal or something.


I found it interesting that the answer wasn't vacuum, since in a vacuum it would be 0... that was my rationale for picking vacuum... but apparently 0 doesn't count as a slow speed..

 

[Pre-Med Village]

So there was this question in the BR that bugged me... it asked through which medium sound waves will travel the slowest.

Listed were a vacuum, water, air, and some metal or something.


I found it interesting that the answer wasn't vacuum, since in a vacuum it would be 0... that was my rationale for picking vacuum... but apparently 0 doesn't count as a slow speed..

BR is the best, though there will still always be a real MCAT question, and good questions of good authors in MCAT prep can miss in this way. Because there isn't the beta testing with the population of test takers, which spots these by a drop off in correct answers among the most advanced students, this question is too clever by half. It's trying to teach a bit of science - speed of sound is fastest where the ratio or sqr rt of bulk modulus to sqr rt of density is greatest, and it's trying to teach a bit of test-taking wisdom. If you try to make a true statement from the wrong answer you are inclined to pick, you actually have a statement which is a' priori nonsensical. Having no speed in vacuum, you could never measure the speed of sound there, etc. etc., so there could be no empirical scientific data, yackity yack, but I have a feeling there would be an outlier group with the question, who would otherwise be on the way to 11s and 12s, who would uncharacteristically miss this one, so it probably wouldn't make the cut through AAMC's own question validation process to the final exam. I could see advanced students being tempted either way because of a dissonance in trying to understand the question writer's intentions. I had a question on my own physical sciences MCAT a long time ago - a 14 in 1994. I am convinced that question was being beta tested from similar reasoning because I couldn't believe AAMC really understood the curve ball it was throwing. Usually if you can put the question in the right conceptual frame of reference in terms of science, on the real MCAT the right answer is apparent. The test writer's intention is useful for finding the scientific frame of reference, but there aren't as many questions with a purely tricky component as you will find in MCAT prep literature.

 

[samvillian]

Thank you, sir.

 

[whiteshadodw]

LOL. if it makes you feel better i missed this one too for the same reasoning. i guess it made me realize that longitudinal waves just cannot exist in vacuum. on the other hand, i think transverse waves can occur in vacuum.

 

[ThirdEye]

I missed it too, but now that I reflect.... it's asking where it will travel the slowest. If it doesn't travel, it doesn't fit the criteria for being a true statement. I've seen b.s. questions like this in EK VR 101.

 

[muhali3]

LOL. if it makes you feel better i missed this one too for the same reasoning. i guess it made me realize that longitudinal waves just cannot exist in vacuum. on the other hand, i think transverse waves can occur in vacuum.

only EM waves.