Errors on AAMC 9 (for those who have taken it)?

[odddodo]

I just took the physical sciences section of AAMC 9, and there seems to be a couple possible errors (if I understand correctly) on some questions.

Question 37: This problem deals with an experiment where a rotating tire is brought to a stop. The AAMC solutions guide says that the answer is B, that the kinetic energy of the tire is equal to the work required to bring it to a halt. However, the question stem asks what the relation between the translational motion energy of the tire and work required to stop the tire is. Wouldn't the work required be more than the translational motion energy because there is also rotational energy that needs to be taken into account?

Question 71: This problem deals with explaining why light travels slower in a denser medium than in air. The solutions guide gives the answer as A, that the atomic structure of the dense material absorbs and re-emits the light, slowing it down. The guide says that answer B is wrong because the nucleus does takes part in the light absorbing and re-emitting. However, choice B in the test is that the nucleus takes part in the absorbing and re-emitting. In other words, the solution guide is just reaffirming the choice, not refuting it. This effectively gives the problem two correct answers.

Am I misunderstanding something here, and if so, could someone explain?

And another question: If the AAMC does make such mistakes on the practice tests, how can we be sure that all the test questions on the real thing are correct? Is there any kind of feedback system in place?

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[Sol Rosenberg]

Question 71: This problem deals with explaining why light travels slower in a denser medium than in air. The solutions guide gives the answer as A, that the atomic structure of the dense material absorbs and re-emits the light, slowing it down. The guide says that answer B is wrong because the nucleus does takes part in the light absorbing and re-emitting. However, choice B in the test is that the nucleus takes part in the absorbing and re-emitting. In other words, the solution guide is just reaffirming the choice, not refuting it. This effectively gives the problem two correct answers.

Am I misunderstanding something here, and if so, could someone explain?

And another question: If the AAMC does make such mistakes on the practice tests, how can we be sure that all the test questions on the real thing are correct? Is there any kind of feedback system in place?

For #37, Before the brakes engage, the rotational kinetic energy of the wheel must equal the translational kinetic energy of the wheel, because the translational motion of the wheel is simply caused by its rotation. Therefore, the work necessary to stop it must be equal to the translational/rotational kinetic energy of the wheel before the brakes are engaged. AFTER the brakes are engaged and the wheel skids, the ratational kinetic energy = 0, and the translational kinetic energy is non-zero.

The explanation for the solution to #71 is correct and consistent. The nucleus does not absorb/release energy in non-nuclear (fission, fusion, etc) reactions. Choice B is wrong because it has the nucleus absorbing/releasing energy in a non-nuclear reaction. The electrons of the atoms of the medium absorb the energy by being excited to higher energy levels, so choice A, which states that the atomic structure absorbs the energy is correct.