Physics Passage on the MCAT – Breaking it Down

Introduction

Dr. Ryan Gray: The MCAT Podcast, session number 22.

A collaboration between the Medical School Headquarters and Blueprint MCAT (formerly Next Step Test Prep), The MCAT Podcast is here to make sure you have the information you need to succeed on your MCAT test day. We all know that the MCAT is one of the biggest hurdles, and this podcast will give you the motivation and information that you need to know to help you get the score you deserve so you can one day call yourself a physician.

Welcome to The MCAT Podcast, part of the Med Ed Media network. You can find out all of the shows that we do over at www.MedEdMedia.com. That’s www.MedEdMedia.com.

This podcast is going to break from our standard, or what we’ve been doing on The MCAT Podcast, and start diving into questions, actually breaking down MCAT questions, and going through the questions, and talking about them, and figuring out how to get to the right answer. While that doesn’t necessarily work 100% for an audio podcast, we’ve tried our best to make it work so that as you’re listening to this in the car, or while you’re working out, you’ll get the most out of it. But you can also go to our show notes page specifically for this episode and the episodes coming up because we have several in a row where we’re going to do these types of questions. If you go to www.TheMCATPodcast.com/22 for episode 22, then you can download the actual questions, a PDF of the question that we’re going over, so you can read along with us and actually see everything right in front of you. So again that’s www.TheMCATPodcast.com/22.

So Bryan, are you ready to break into some MCAT questions?

Breaking Down a Physics Question

Bryan Schnedeker: Yeah absolutely Ryan, and the one we want to look at today is the physics passage one handout, and so if folks are listening to the podcast and can get the handout, that’d be great to follow along. What I’m going to do is actually I’m just going to start by reading the question that we’re going to solve together. So the question says, ‘Which of the following waves would have a wave length larger than any standard electrospun fiber.’ So this question comes with a passage and reading the question itself, ‘a wave length larger than electrospun fiber,’ you can go back to the passage and start skimming through looking for some information about wave lengths rather than doing a whole big analysis of the passage at the beginning. So again if you’re following along with the handout you can go ahead and do that, but if you’re listening I’ll just jump right to it and read you a little selection from the passage that would answer this. So this is coming out of paragraph two here. It says, ‘Fibers obtained may have diameters ranging from 0.05 to 5 micrometers. The small diameters provide high surface area to volume and high lengths of diameter ratios. The process has applications in providing scaffolds for tissue engineering products.’ Okay so you go back into the passage and you get that number, 0.05 to 5 micrometers, and again the question was a wave that would have a wave length larger than an electro spun fiber. And the answer choices are red light, blue light, microwaves, and x-rays. Now here’s where the strategy note comes in. If this were a science classroom, kind of studying for a physics midterm type situation, you would probably want to immediately jump to start doing calculations, right? You would pull in some of your outside knowledge about the electromagnetic spectrum, and the wavelengths, and maybe you would treat this as a unit conversion problem, you would think about oh normally the electromagnetic spectrum is described in terms of 350 to 700 nanometers or whatever, and you look at these micrometers, and you would start trying to do a whole bunch of math. But we want to remember of course on the MCAT that it is a reading and reasoning test that just happens to be about science, rather than a science test. So now I’m going to read the question one more time. ‘Which of the following waves would have a wave length larger than any of these fibers?’ So notice by the wording of the question itself, the answer choice has to be the wave with the longest or largest wave length. Because if a particular answer choice is larger than electrospun fiber, there can’t be any other answer choices that are also larger than electrospun fiber or there would be two right answers, and of course on the MCAT we know there’s only one right answer here. So by reading the wording of the question carefully and thinking about the logic of the question rather than obsessing over doing a whole bunch of math, you can look at this and say, ‘Oh really a wave length larger than the fiber, I just need the largest wave length or the longest wave length here.’ And again the answer choices were red light, blue light, microwaves, and x-rays. And the MCAT is going to expect you to know your physics, know your electromagnetic spectrum, and know that microwaves of those answer choices I listed have the longest or largest wave length.

Okay red light would be longer wave length than blue light, blue light is the shortest or violet light is the shortest on the visible spectrum. And then of course x-rays are very high energy, very short, very small wave length, very high frequency, so x-rays would be the other end of the spectrum. So again Ryan, one of the things we see over and over again on the MCAT is that if you do your reasoning correctly on the question and the wording of the question, and you have a good solid grasp of your outside knowledge, you don’t have to do nearly as much calculation or heavy duty analysis as you think you might need to. And so the answer ends up being microwaves.

Dr. Ryan Gray: Interesting. So these are going to be fun for me because I’m coming into it having forgotten all of this information. So when you say that, what I’m looking at- so you talked about the question is saying, ‘larger than any standard electrospun fiber.’ And so it says that fibers range from 0.05 to 5 micrometers, so how do you- how do you go from having that number to just throwing out red light, blue light, x-rays because they’re smaller than microwaves? How do you know that those other answers aren’t smaller- or how do you know those other ones aren’t larger than that 5 micrometers?

Bryan Schnedeker: Right sure, so if blue light were the right answer, if blue light had a wave length that was larger than a fiber, larger than 5 micrometers, then red light would also have a wave length larger than 5 micrometers because this is from outside knowledge. We know that blue light is high energy which means high frequency, which means short wave length. By contrast red light is low energy and a low frequency, and therefore very large wave length or long wave length. So if blue light were the right answer, then red light would also be the right answer, they would both be larger than 5. So you can’t have two right answers, so by that logic blue light is out. Now we can apply the same step in the logic, right? So if red light were correct then microwaves, which are even more low energy than visible light; very, very low frequency, very long, very wave length. If red light were the red answer then microwaves would also be larger than 5. So from that process or pattern of elimination you can say if they want a wave length that’s larger, let me just pick the largest one here and I’m done.

Dr. Ryan Gray: I like it. I like it. A fun trick to remember that I used to remember that microwaves are large waves is truly a microwave, that appliance that we have in the kitchen. That basically the microwave when you’re looking through it has this metal screen in front with holes that you can see through, and the waves are so big that they can’t pass through the holes. So I always find it funny when people are scared of standing in front of the microwave because they’re afraid of the microwaves like doing something to their body when it’s basically a big [Inaudible 00:08:41] cage sitting there.

Bryan Schnedeker: Absolutely. And yet they’ll say, ‘I don’t like to stand in front of the microwave,’ and they’ll tell you that while holding their cell phone up to their ear which uses microwaves for the cell phone signal.

Dr. Ryan Gray: Exactly. Alright well that was an interesting one. I’m really excited to dig into more of these next week and moving on for the next couple weeks.

Bryan Schnedeker: Fantastic. Me too, Ryan.

Final Thoughts

Dr. Ryan Gray: Alright there you have it, our first episode discussing an MCAT question. So I hope that worked well for you. I’d love to hear your thoughts, you can shoot me an email, Ryan@medicalschoolhq.net or let me know in the Hangout. If you’re not part of the Medical School Headquarters Hangout, you should be. It’s free, it’s a Facebook group specifically for premed students to collaborate, and discuss, and help each other. Go to www.MedicalSchoolHQ.net/group.

If you’re like most premed students planning on taking the MCAT this coming year because you’re applying this coming year, then right now is the time to start thinking about MCAT prep. Go check out Next Step’s MCAT course over at www.NextStepMCAT.com. Don’t forget to use the promo code MCATPOD, that’s all capital letters, MCATPOD to save some money on your checkout, in your checkout. Whether you’re buying the course which is their new course that has hundreds of hours of material, and live office hours with the people that actually made the course and not just random teachers, you’ll get everything that’s offered for cheaper than those other big box MCAT test prep companies. Go check them out, www.NextStepMCAT.com.

Alright I hope you got a lot of great information out of our podcast today. Again, let me know how this format worked. Don’t forget to go to the show notes page at www.TheMCATPodcast.com/22 to download the actual question so you can read along with us if that’s something you would like to do, and next week we’ll have some more questions to talk about.

So enjoy your week, have a Happy New Year, this is the last episode we’re doing in 2016, we’ll come back with you the first week of 2017 with more great information so you can crush the MCAT.