MCAT这些物理不花时间复习，想不费力真的不行

其他不敢提插不上嘴，物理自己懂。本想批评娃的，但一看MCAT这些物理没花时间复习真的不行。

这道题算简单直白的问题，让我答也答不对。真想不通学文科的学点物理能回答吗？

Question 11

Which of the following explains why the pitch of person’s resonant voice harmonics rises when they inhale helium instead of air?

A.

The wavelength increases due to the change in temperature from the helium atoms.

Show Explanation

B.

The change in timbre results in a higher perceived frequency of the voice.

Explanation：The pitch of a perceived sound is dependent on its frequency. In the case of the human voice, there are many overlapping waves with various frequencies and higher harmonics of those frequencies. Nonetheless, the basic fact remains that pitch depends on perceived frequency. Thus, when helium atoms are inhaled, the density of the air is being changed, which alters the timbre (an overall quality of voice that results from overlapping waves) to emphasize the higher-pitched harmonics. We perceive that as a high-pitched, "squeaky" voice. However, note that even without knowing the definition of timbre, this question can be solved by eliminating the other options.

C.

The frequency decreases due to the change in air density from helium atoms.

A decrease in frequency would result in a lower-pitched, deeper voice, not a high-pitched squeaky voice.

D.

The speed of the sound wave remains constant regardless of changes to the medium through which the sound wave propagates.

Show Explanation

所有跟帖： 

• MCAT以前考物理吗？ -study169- ♂ (0 bytes) () 12/21/2020 postreply 12:28:41

• 考 -成功的兔- ♀ (0 bytes) () 12/21/2020 postreply 12:29:45

• 考的物理数学知识肯定不难 -wzg69- ♂ (171 bytes) () 12/21/2020 postreply 12:31:16

• 至少要花一两个月准备，还要学一点窍门 -study169- ♂ (0 bytes) () 12/21/2020 postreply 12:36:58

• 据俺娃说MCAT改革之前... -娃无完娃- ♂ (122 bytes) () 12/21/2020 postreply 12:39:44

• 是，我娃做过一次老题，物理化学结果好很多 -wzg69- ♂ (38 bytes) () 12/21/2020 postreply 12:41:30

• 声学啊。好像在AP里有 -greenoasis- ♀ (0 bytes) () 12/21/2020 postreply 12:44:04

• 这B的解释并不好把 -wzg69- ♂ (1814 bytes) () 12/21/2020 postreply 13:25:54

• 解释不太好，但没错。你的解释可是错的，别把娃带沟里了：） -淘娃羊爸- ♂ (315 bytes) () 12/21/2020 postreply 14:02:24

• “媒介密度越低，波长越小”：查了一下这是错的 -wzg69- ♂ (100 bytes) () 12/21/2020 postreply 15:07:02

• 你还是没搞清楚 -淘娃羊爸- ♂ (150 bytes) () 12/21/2020 postreply 20:22:19

• 學過弦樂器的也能答對 -violinpiano- ♂ (177 bytes) () 12/21/2020 postreply 12:36:20

• 老兄太焦虑了吧，这些都是常识啊。 -淘娃羊爸- ♂ (187 bytes) () 12/21/2020 postreply 12:49:49

• 这得涉猎很广，是sicence bowl的路数 -wzg69- ♂ (465 bytes) () 12/21/2020 postreply 13:06:09

• 是不是还是得上补习班或者做补习书。总之就是得熟悉这考试风格 -greenoasis- ♀ (0 bytes) () 12/21/2020 postreply 13:18:17

• 感觉得这样 -wzg69- ♂ (29 bytes) () 12/21/2020 postreply 13:34:05

• 旧形式的补习书多，但现在改了。补习班因人而异吧？当初孩子没上补习班，倒是自学了一些病理学。 -孤鹜晚霞- ♀ (0 bytes) () 12/21/2020 postreply 14:12:57

• 你不行不等于孩子不行，别瞎指挥。提供美味营养的三餐和一个舒适安静的学习环境足以。 -孤鹜晚霞- ♀ (0 bytes) () 12/21/2020 postreply 13:54:47

• 网上有考古题，也可以网购最新的复习题(这个放到后面用)。没有你想得这么困难，如果平时都学到了。 -孤鹜晚霞- ♀ (0 bytes) () 12/21/2020 postreply 13:59:13

• 考的就是nextstep mcat diagnosis -wzg69- ♂ (133 bytes) () 12/21/2020 postreply 14:30:28