# Physics Basics for Pre-Meds

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Physics Basics for the Pre-Med

#### Table of Contents

Physics is a pretty difficult topic for most pre-medical students. That’s probably because it is rather different then the other classic pre-medical courses. In this post we’ll review why pre-med students have trouble with the class, strategies that’ll help you do well, and some of the topics you’ll cover while studying physics. As with all of our articles, this will only cover the basics. It’s up to you to do the work, but we hope you’ll find this mentoring helpful!

## 7 Reasons Pre-Medical Students Have Trouble with Physics

1. It’s very math-focused. Unlike biology and physiology, but similar to chemistry, you frequently. need to translate what you’re reading into mathematical terms.

2. Physics is extremely conceptual. It’s hard to visualize many of the concepts covered in physics; waves, vectors, Newtonian laws of motion, etc. Yet, visualization is absolutely critical to success on exams.

3. They take physics before they are ready. Doing well in physics depends on you having a solid math background. Pre-Calc is the minimum and many physics sections will require calculus. *Make sure you find out if your school offers different levels of physics – the calculus version and the pre-calc version. For students who feel strongly about their math skills, many people recommend the calc version over the pre-calc version of the class.*

4. Students underestimate physics. I’ve seen it countless times. A student will take physics along with 4 other difficult science classes. Since physics is so unlike most other classes, it tends to be the odd one out and grades in that class suffer.

5. Help is sought too late. Never wait until you’re having trouble to get tutoring. The time to reach out for advice from tutors is at the very start of the semester. You want to be pro-active in how you approach your work, your studying, and your test taking!

6. Not enough practice problems are done. Physics, out of all the classic pre-medical classes, requires the most practice problems. Sure, with Orgo and Chemistry you should also be doing problems – __but physics is all about memorizing those formulas and knowing how to apply them__!!

7. You don’t understand how the material will be tested. This is another common error. Will the exam have problems to solve? Terms to define? Multiple choice? A mix of all of these? If you are doing practice problems to prepare for the exam, make sure your problems reflect the exam itself.

##
**Why is Physics a Pre-Med Class?**

Let's talk about the applications of physics in medicine before we go any further. With biology, biochem, chemistry, and orgo the connection is a little clearer. However, with physics it can often be taken for granted. Let's look at a few areas where physics is incredibly important to the study of medicine.

**Human Bodies Obey the Laws of Physics**: Many of the examples we’ll point out below are built upon the understanding that there’s nothing magical about how the human body works. Every breath of air, every muscle action, every step we take, and every electrical impulse can be explained by physics.**Gas Exchange:**The**respiratory system**is driven by pressure gradients and the**cardiovascular system**. Understanding gas and fluid laws is incredibly important to understanding both systems.**Shock:**The different types of shock that a body can undergo (hypovolemic, cardiogenic, etc) can only be understood if you understand Circuits and the Cardiovascular System. Pay special attention to circuits arraigned in series vs parallel!

4. **Filtration**: All you future nephrologists out there are going to need to understand how that loop of Henle works to filter our blood. Physics will provide that understanding!

5. **Our Amazing Musculoskeletal System: **Our bodies are incredibly complex combinations of type I, II, & III levers intertwined with even more complex neurological circuitry. Orthopedics, Geriatricians, OMM specialists, and PMR docs in particular need to understand levers, center of gravity, and friction.

**6. Radiology & Nuclear Medicine:** I hope you didn’t think radiology was just zapping people with x-rays and looking for broken stuff. This is another domain you’ll be studying in detail with physics.

## Ok, ok, enough with convincing you that physics is important...

Let’s look at some of the topics you’ll cover in a typical first semester physics class!

- Vectors
- Newton’s Laws of Motion
- Work, Kinetic Energy, & Potential Energy
- Momentum, Impulse, and Collisions!
- Rotation and Periodic Motion
- Waves & Sounds

This can seem like a lot, but don’t get overwhelmed. The trick to tackling physics is developing an effective approach that works for you. Use the same approach for every topic! A classic approach might be…

- Pre-read about the topic about a week before it’s introduced in class. Along with reading, watch some YouTube videos from trusted sources like Khan Academy. This serves as a primer.
- Schedule a tutoring session for the same day as your physics class, or the day after. Basically you want to review the material
**with a guide**within 24 hours of learning it. - Repeat any example problems you did in class on your own. Your teacher picked those problems for a reason – either they were good for introducing the material or they reflected the level of complexity they expect you to know for the exam.
- Do your homework early! You basically don’t want to procrastinate on your homework. Instead do it early, redo it for practice, then find even more problems to do.
**Try not to do your homework with your tutors.**Only if you are really stuck or don’t understand something should you bring homework to your tutor. Instead use the time with your tutor to have them test you. This’ll increase your exposure to different problems.

"Don't feel overwhelmed, the trick to tackling physics is developing an effective approach that works for you. Use that same approach for every topic!"

## Vectors

*A vector is something that has both magnitude and direction.* This simple sentence is both the start of physics and the start of many student’s confusions. If you get confused at any time during class, make sure you ask your teacher to explain what a ‘magnitude’ (size) is!

Understanding how to utilize vectors is critically important in the early stages of physics. The difference between speed and velocity is one that is commonly tested to make sure you understand vectors. You’ll also need to be able to add, subtract, and utilize vectors in 3 dimensions!

## Newton's Laws of Motion

The Newtonian laws of motion are where physics starts to get really confusing for most students. It’s not as simple as memorizing the 3 laws – that’s the mistake many pre-med students make. Always remember, physics is not tested the same way biology is! You’ll need to be able to apply these laws using formulas. You’ll also need to fully understand how to get to the formulas after being given seemingly unrelated information.

This last part is often what confuses students the most. Consider the formula F = ma, aka Force = mass x acceleration. Anyone who can do simple algebra can find F when given m and a. However, can you find F when instead all you get is a scenario describing falling bodies on the planet Mercury? Be prepared for some tricky mental gymnastics! Be prepared to learn a number of different formulas related to the Newtonian laws and know them forward and backwards!

When studying physics you should be able to derive EVERY SINGLE VARIABLE in a formula. Often half the battle is learning how to get to F when neither m or a is given.

## Work, Kinetic Energy, and Potential Energy

These topics are perfect examples of topics that can be deceptively difficult both conceptually and practically. Many students think that work, kinetic energy, and potential energy are easier concepts to grasp. However, you should expect to do a lot of *work* solving these problems!

**Work**: When a force acts upon an object causing displacement. There are three elements to work; displacement, force, and cause.

*Think of a massive boulder, you push and push and push on the boulder but it doesn’t move at all. Is work being done? ***No. While there is a force and a cause, we have no displacement occurring. **A lot of students confuse with the colloquial definition of work with the physics definition. Don’t be that student! To get more practice with work check out this link!

**Kinetic Energy**: KE = 0.5 * m * v^{2 } where m = mass and v = the velocity of the object. (See where they can connect vectors back to KE?) This is the energy of motion. Of course it gets much more complicated then this and keep in mind that this is entirely a scalar quantity (it has no direction unlike work!) This is the type of energy behind injuries such as concussions, coup-contrecoup injuries, and axonal shearing injuries. You’ll learn more about these forces in the next section!

**Potential Energy**: U = m*g*h where m = mass, g = gravity, and h = height. Potential energy doesn’t describe a pre-med student taking a nap. Rather, it describes a positional kind of energy. This is another amazingly complex topic and the principles of it are utilized in things like hydroelectric storage facilities.

## Momentum, Impulse, and Collisions

So much of what you’ve learned has led up to this point. All that information and all those calculations with energy, movement, force, etc allows you to really understand these concepts.

**Momentum**: p = m*v where p = momentum, m = mass, and v = velocity. The formula itself really tells you all you need to know about momentum, the bigger an object is, the more velocity it has the greater it’s momentum. Think about an elephant on roller skates and a mouse on roller skates both traveling at the same velocity. Which has more momentum? Of course the elephant will!

**Impulse**: This is a trickier concept to get. Think about Newton’s second law which comes down to F =m*a and remember that acceleration = velocity divided by time. If you multiply both sides of the force equation by time, you get a brand new equation! F * t = m * v. This new equation represents impulse. **Impulse is change in momentum. **This allows you to move onto the next concept – **collisions**.

**Collisions**: Here you’ll learn about perfectly inelastic, perfectly elastic, and inelastic collisions. Always keep in mind that momentum is always conserved with collisions.

**This writer found that impulse and collisions are easily one of the hardest concepts in physics to grasp. Why? It’s a difficult concept, plus it is often taught mid-semester when all the other difficult classes are getting harder too. **

**Pro Tip**: Anticipate this difficult topic and try to start reviewing it a few weeks earlier. Make the time for this review and you’ll be thanking yourself later!

## Rotation & Periodic Motion

Both of these topics also tend to be very difficult for pre-med students. Again, the difficulty is often related to the need to tie highly conceptual ideas with concrete formulas.

**Rotation:** At this point in your physics class you’ll start wishing that things only traveled in straight lines. Don’t get overwhelmed though by the introduction of new variables like angular acceleration and angular velocity. You can tackle it by using the same systematic approach you’ve taken so far. **Definitely set aside time to memorize the equations – even if you don’t have to!** Memorizing those equations will help you really understand what’s going on.

**Periodic Motion**: This is another concept that has many medical implications. Ultrasound and hearing are a great examples. Other non-medical examples include a swinging pendulum, a rocking chair, tuning forks, etc. You’ll be exploring concepts such as periods and amplitudes while studying periodic motion. Conceptually it’s probably going to be easier then rotational physics.

## Waves & Sound

Just as previous topics built on earlier concepts, waves and sound will build directly from periodic motion. Again, Ultrasound is a classic medical example of how this physics concept is applied. Prepare to review concepts such as amplitude, rarefactions, compressions, and the difference between mechanical and pressure waves.

**Tips: **This is usually part of the home stretch for Physics I. Get started early on these concepts and don’t underestimate the role that trig plays in studying these concepts.

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