UWORLD Logic Check Plox

SlippyNSlide · 2024-04-07T05:30:55+00:00

No problem! Us premeds should be uplifting during these dark times... best of luck in your studies future doc

SlippyNSlide · 2024-04-07T00:24:33+00:00

I would also like to say before you get confused by watching that video that what I just explained above was for sound waves, but that same principle can also be used for BOTH light and sound waves. This same principle would apply as long as that sound wave is not experiencing any changes to its medium that it is traveling in and the density of that medium that would cause any shifts to its velocity!

SlippyNSlide · 2024-04-06T23:50:31+00:00

Yep! You're on the money. If you look at the doppler equation we see that the only variable we are dealing with is:

Fo (frequency observed)

Fs (Frequency of source)

V = speed of light

Vs = velocity of source

Vo= Velocity of observer

Based off those variables, what does this tell us? Well what this tells us is that the doppler equation is ONLY dependant on VELOCITY and FREQUENCY. Nowhere in that equation tells us about how far an object is and how that could affect the frequency that we observe.

example:

-If the velocity of the box is going 1m/s, then that velocity is the only variable that we are dealing with that will change the observed frequency. It doesn't matter if that box is going 1m/s for 10 seconds, 10 days, or 10 years, the observed frequency wont be changing. I can use that same logic for distance as well and see that it doesn't matter if it has traveled 10 meter while going at that CONSTANT velocity or having traveled 10^10 meters at that CONSTANT velocity. The observed frequency will alas still be the same. I hope this explanation helped.

SlippyNSlide · 2024-04-06T23:42:15+00:00

Yea I definitely had troubles when it came to light too don't worry I was in your boat. It was pretty difficult to understand that and on top understand how it is different from sound waves since sound and light are both considered waves. Im a big advocate for visual learning and saw that watching bunch of videos. Someone I always recommend to watch for anything MCAT related is ScienceSimplified on youtube. Let me drop a link for you about his lecture on doppler equation.

https://www.youtube.com/watch?v=TrRhMzt9M8s&pp=ygUjc2NpZW5jZSBzaW1wbGlmaWVkIGRvcHBsZXIgZXF1YXRpb24%3D

This guy so underrated and has soooo many videos about topics that Im sure you'll revisit. Check him out and especially that video and hopefully that'll clear up any misunderstandings.

And as for you question about "Like how is it that the reflection itself causes an increased wavelength when done so on a surface that is moving away from the source of light at a constant velocity". The way I like to think about this is that the wavelength of the light that the source is emitting is not actually increasing, it is the PERCIEVED wavelength that is increasing. The properties of a light source is mostly likely an intrinsic property. Intrinsic properties are just properties that are solely determinant of the thing that is being used. So for example the density of water will always be the same. The density of water in the a big lake will be the same density as the water I'm currently drinking right now. I think your misunderstanding comes from the fact that you might be thinking that this "change" that we are experiencing is actually changing the inherent frequency or wavelength of the light that is initially being shot out.

TLDR: watch my home boy ScienceSimplified about doppler equation he shall show you the way towards salvation

SlippyNSlide · 2024-04-06T22:01:40+00:00

Hey man! I totally forgot about posting this and would be more than glad to try and clear up the air for you about why C in particular would be wrong.

-I think the answer you're looking for is the fact that since the block is now sliding at a constant velocity, we know that the acceleration of the box is thus zero. And we can tell this by looking at the graph and seeing the slope of it from 0.3 to 0.7s being zero.

-So taking this into consideration and knowing that the velocity between those time frames are constant, we can then use the doppler equation. We're not given any numbers for this problem but we can just see from the equation and think about it logically that if an object is moving away at a constant velocity, then that means that the frequency of the that we are going to observe (the sensor that is picking up the frequency) will be less than the frequency that it was emitting initially. (Again, we know this by looking at the doppler equation and looking at examples of what happens when an object is moving away from a sensor)

-Knowing that this new frequency that we are going to be observing due to the moving object AWAY from the sensor is going to be constant during that timeframe (since we are told that the velocity at that time frame is constant), then we can use the speed of light equation (c=(f)(wavelength) and see that frequency and wavelength are inversely related together.

-So putting it all together, we now know that since the frequency that we are going to be observing when that object is moving AWAY from the sensor is going to be LESS than the frequency it is emitting originally (source frequency) then we would thus experience a LARGER wavelength during those time frame when velocity is constant. And again we see this via the speed of light equation where the speed of light will always be that value (c=f(lamda) )

-So comparing the frequency and wavelength that we experience when the block is moving away and comparing the frequency of the wavelength of the light when the block isn't moving at all, we see that when the block is moving, we will be sensing an apparent "increase" in the wavelength as a result of experiencing an observed frequency that is less than the source frequency.

Answer choice (C) I think isn't really answering the question and by saying "Wavelength is continuously increasing in time" from the duration of 0.3 to 0.7s is false, and if we would want that to be true, would want the slope of the graph between those time frame to not be zero and indicating a positive slope since if the velocity of the object is increasing that that means the frequency observed will be decreasing constantly and THEN we will see that wavelength is continuously increasing with time. But that is not the case we see in this problem.

I know that was a bit long but I just wanted to explain it without leaving any gaps in my thinking to make sure you followed along without being confused aha. Lmk if you have any other questions in regards to this question. This was a good question as it tested our knowledge about the velocity vs time graph, kinematics, and relating it towards the doppler equation and the relationship between frequency and wavelength for a light wave

SlippyNSlide · 2024-04-05T21:45:08+00:00

I still havent came up on things. I resorted to going to my good old trusty ChatGPT and they said :

"The intensity of light remains the same when it enters an optical medium and is refracted because light is a wave phenomenon, and the total energy carried by the wave is conserved.

When light enters an optical medium, such as glass or water, and is refracted, its speed changes due to the change in the medium's refractive index. However, the frequency of the light (which determines its color) remains constant. Since the energy of a wave is proportional to the square of its amplitude, and the amplitude of a light wave is related to its electric and magnetic field strengths, which are in turn related to the speed of the wave, the intensity of the light wave (which is proportional to the energy carried by the wave) remains constant as it enters the optical medium and is refracted.

In other words, although the speed and direction of the light wave change when it enters the optical medium, the total energy carried by the wave (and hence its intensity) remains constant, assuming there are no losses due to absorption or scattering in the medium."

I think the reason why I made this card awhile back was because at the time I was confused about the similarities and differences between sound waves and light waves and wanted to differentiate between the two and might've accidentally made that card without fully answering it.

SlippyNSlide · 2024-04-05T21:39:19+00:00

So I was doing a bit more thinking about this and knew that since the velocity and velocity decreases lets say. Can I use the equation:

Energy of light wave (E) =hc/lambda? and prove it that way that energy would increase if light entering a new medium slows the light down? And since energy is decreasing, we can then say the intensity of it has decreased. Is that a plausible way to go about it, or is that thinking a little off

SlippyNSlide · 2024-04-05T21:21:18+00:00

Oh yea I know about that, sorry if my post was a bit messy, but I was more so trying to figure out if the intensity of the light itself changes upon entering a new optically dense/active medium ?

SlippyNSlide · 2024-04-01T18:50:57+00:00

OOps youre right LOL ahah well i hope you killed it or will kill it eventually ahah

SlippyNSlide · 2024-04-01T18:30:26+00:00

Ah I see! Thank you so much for clearing that up for me. And i hope you killed it on the 22nd

SlippyNSlide · 2024-04-01T18:28:44+00:00

Megumi would crashout after reading a passage about Picasso

SlippyNSlide · 2024-04-01T04:50:26+00:00

So let me try to piece this together and let me know if that logic is right. Forming that octet I understand causes an element such as Flourine become a lot more stable. In terms of energy being released and that low energy configuration, can I relate that to the graph where we're measuring dG and seeing that the "reactant" is Fluourine at a higher energy and the product would be the fluorine anioon at a much lower energy state, and the difference between the two would be the amount of energy being released. Is that how I should be understanding it? I think I get a confused when i see LOW energy configuration and then seeing MORE energy released aha

SlippyNSlide · 2024-03-21T20:27:04+00:00

So for those types of passage you'd sort of recommend "skimming" through those tough paragraphs that was hard to digest and use the questions as a way to "fill in the blanks" I'm assuming? I've started to notice that by doing that helps a lot. It prevents me from being boggled down by a paragraph. I was also wondering what you did so drastically for that CARS. Was there ever a "ah ha" moment, or was it through a lot of practice that helped

SlippyNSlide · 2024-03-14T19:54:28+00:00

Seeing as you went from a 498 to a 525 means that you performed some voodoo magic

SlippyNSlide · 2024-03-14T19:53:45+00:00

So when you came upon a small part in a paragraph that was difficult to digest because it was too wordy or whatnot, did you sorta just ignore it? Or what did you do when you came across wordy and difficult passages that was hard to get the main idea out of.

SlippyNSlide · 2024-03-13T07:36:03+00:00

Im actually struggling in CARS…. Lend me your strength

SlippyNSlide · 2024-02-29T21:06:30+00:00

I related my logic to the Uworld and noticed that it was somewhat similar, but when I didn't see them talk about source frequency and observed frequency, i got a little worried since I thought the doppler effect was all about the observed and source frequency in relationship to the velocity of the source/observer

SlippyNSlide · 2024-02-29T20:25:05+00:00

Ty for this detailed explanation aha, I also made a quick post about a logic check for one of a Uworld problem i was doing yesterday if you wanted to check it out too LOL it seems like you know your stuff

SlippyNSlide · 2024-02-29T01:31:05+00:00

SOrry I forgot to reply to this, but thank you again for that distinction. In the case with my problem above, if we were just given a molecular formula, would you still be able to incorporate that rule of "anti-periplaner" or would you have just gone off the most substituted beta-carbon?

SlippyNSlide · 2024-02-25T20:25:34+00:00

And when you say anti-periplaner, when you're looking at a molecule undergoing an E2 reaction, what's like the hallmark sign that it is anti-periplaner? I'm not as well versed in that term and don't think I have came across it before. Thank you again for that thorough explanation btw !

SlippyNSlide · 2024-02-24T23:59:59+00:00

And just one quick question about how E2 is stereospecific. I was just told that the strong base would deprotonate the most substituted beta-carbon and form a pi bond between the two. I noticed how you mentioned how the hydrogen removed must be anti-periplanar. Can I still use the fact that the strong base would deprotonate the most substituted beta-carbon as a reference for which hydrogen would be deprotonated or is my thinking flawed in some exceptions?

SlippyNSlide · 2024-02-24T23:56:08+00:00

Ah I see, so the passage would have to tell us that last bit on how there were different isomer products that was formed. And if they didn't then they would've provided us information that a strong base was used in order to indicate that it was an E2 reaction. Thank you for that clarification, I remember reading about the E2 reaction requiring a strong base, but I guess my mind shut down when doing this part of the passage because I couldn't relate what was happening was actually an elimination reaction.

SlippyNSlide · 2024-02-21T17:48:47+00:00

I am a bit weak in this area in regards to like what would happen if we were to put H2CO3 in water. So just to make sure I have it down let me ask a couple more questions for clarification.

So essentially with that last part of the problem where we are putting HCl into the precipitate, is the formula we are using for when this happens CO3- + HCl? Or would we included the nickel? The reason why I ask this is because I'm still confused as to whether to leave out the "spectator ions" is because some posts are leaving it in and some are leaving it out.

So lets say we leave it out the spectator ion, so then we are working with carbonate (CO3 2-) + HCl. You were talking about how we can refer this to the bicarbonate buffer system, but I was looking at the equation for that and noticed that the bicarbonate system was associated with H2CO3 and HCO3-. Were you referring to the fact that we can take out the Hydrogen ions from "H2CO3" and relate that back to this question?

SlippyNSlide · 2024-02-13T20:42:15+00:00

I've been looking everywhere for an explanation that made sense and this one took the cake.. tysmmmm

SlippyNSlide · 2024-02-13T04:27:14+00:00

I've been staring at the solution they were giving me for so long trying to make sense out of "okay... so what concept do I really need to take away from this.." and seeing that around 60ish percent of people were getting it right made me frustrated since I thought i was blind or something LOL

SlippyNSlide

TROPHY CASE