Physics

We found 69 articles

An introduction to potential energy
Potential energy can be easy to understand, tricky to define, and confusing to use. Here, we not only define potential energy, but explain what it means, why physicists use it, how physicists calculate it, and examine why potential energy is only associated with certain types of forces.
Mastering MCAT physics problems through dimensional analysis
Preparing for the MCAT can be an overwhelming task, especially when it comes to the physics section. Physics concepts, equations, and calculations may seem daunting at first, especially with all the numbers and variables in the test’s complex problems. However, with the right approach, you can tackle this section with confidence and success. In ...
Relativity: from Galileo to Einstein
Imagine sitting in a car and pressing the gas. You can tell you're moving since you feel the car's acceleration and see things moving around you. Once you're traveling at a constant velocity, you no longer feel the acceleration but see the outside world moving around you.
Centrifugal force explained
Fictitious forces such as the centrifugal force are fake forces – they don’t really exist! However, fictitious forces are helpful when working in non-inertial reference frames (a fancy term for reference frames that are accelerating, like when we use the rotating Earth as a reference frame). In these frames, F = ma doesn’t hold, and you’ll need to ...
The Taylor Series
If you’ve taken a high school physics class, you probably started by learning about position, velocity, and acceleration, ubiquitous concepts in physics that are also well-motivated by our daily life experiences. But soon after that, the course probably moved on to less familiar concepts, such as energy and simple harmonic oscillation modeled by ...
Attempting to become a theoretical physicist: initial steps
If you've clicked on this blog, you must be captivated by the beauty of relativity, quantum mechanics, dark matter, or black holes. Now, you're eager to delve deeper into these subjects. Maybe this moment just happened recently or a few years ago. Regardless, you want to get paid to study nature and attempt to describe it using mathematics. As I ...
Escape velocity
Escape velocity is the speed an object needs to escape the gravitational influence of another object. Here, we explain escape velocity, derive the right equation, and discuss what this equation does (and doesn’t tell us) about how objects actually move in space. For example, how fast would you have to throw a tennis ball for it to fly off into ...
How to map the Milky Way with tiny hydrogen atoms
All you’ll need for this project is a computer that can run Python, 30 hours of free time, and an 18-foot aperture parabolic antenna.
Graduate School Qualifying Exams: what are they and how can I prepare?
As a graduate student in a STEM field, your program probably has one or more written qualifying exams which you must pass, along with your oral exams, to earn the coveted title of PhD candidate. The written exams cover the fundamental material in your field—generally from courses you took as an undergraduate or a first-year graduate student. These ...
How to ace intro to physics (using McDonald's)
“One Oreo McFlurry, please.” I hand the cashier my card, take the receipt, and then wait. “Pull up to Window 3, sir, to get your order.” Stretching out in front of me are four windows in a series, one after the other, after the other. But I can't get to the third window without waiting for the car at window two to finish. The system is inane. ...
Electric potentials, fields, and forces
You started your electricity and magnetism course and now all you hear about are potentials, potential energies, fields, and forces. It’s overwhelming. The purpose of this post is to help you understand each of these quantities and how they are related.
Medical Physics: a little known career path
Whenever I tell people what I’m studying in grad school, they seem pleased for a moment, but it doesn’t take long for them to look totally perplexed. It’s as if I told them I study gopher economies.
Quantum Mechanics in 5 minutes
I wouldn’t be surprised if you’ve heard the word “quantum” before. It’s a real buzzword: “quantum computing,” “quantum gravity,” “quantum information,” “quantum entanglement”. But what is quantum mechanics, really? My goal in this post is to give you intuition for what quantum mechanics is, where you can find it in real life, and why it’s so ...
The physics behind hybrid vehicles
The advantage in fuel economy that comes from driving a hybrid-electric car instead of a non-hybrid has not one major contributing factor, but three. Even if you don’t drive a plug-in hybrid, these innovations drastically improve the vehicle’s efficiency using clever applications of physics and optimization.
Capacitor confusion: basic pointers to salvage your sanity
You have recently started to learn about electrical circuits, and even though the occasional, particularly tricky circuit still proves challenging to solve, you feel like you “get” what batteries and resistors are and are starting to grasp fundamental concepts such as voltage and current. Forever dedicated to your torture, your physics teacher ...
Demystifying MCAT physics
Physics can be a very time-intensive section on the MCAT. There are numerous equations to memorize and parse through for each question and it is not always obvious which are relevant. You can waste a lot of valuable time guess-and-checking equations that have the related variables in them. I will illustrate some techniques from personal experience ...
Units: the hints hidden in every physics and engineering problem
In many science and engineering classes, units can be seen as an additional step that needs to be taken into consideration when completing a problem. In some problems on the Fundamental Engineering exam, mismatched units are intentionally used in an attempt to confuse students and measure their understanding of key concepts. Nonetheless, units ...
What if I told you that there’s a way to describe the waves of the ocean, the winds in the skies, the motions of celestial bodies — almost everything around us — and harness that information to create great things? This tool does exist, and it’s a science so fundamental that its principles guide our understanding of everything from microbes to ...
What is a Fermi approximation? The only thing that physicists like more than dimensional analysis is a good order of magnitude estimation, also known as a Fermi problem or Fermi approximation. A classic is the piano tuner problem: “How many piano tuners are in the city of Chicago?”
Working with lenses and mirrors: how to draw a ray diagram
Ray diagrams can look intimidating, but they don’t have to be! In this blog post, we will tackle five examples of ray diagrams.
Having worked through a long physics problem, you finally have an answer. How do you know if it’s right and all that work wasn’t for naught? In this post, I will cover a few quick strategies that can help rule out wrong answers.
What physics equation sheets can do for you, and what they  can’t
In your time taking physics courses, you will likely run into one that deals with equation sheets. These can be note cards or an entire sheet of paper, and anything that can fit on it is fair game and can be brought into a test. The natural reaction might be to try to cram and squeeze an entire textbook on those sheets using really, really tiny ...
The physics of martial arts
As a practicing biomedical engineer and martial artist, I belong to two communities that, at a glance, seem to conflict with one another; engineering requires rigorous thought and thorough validation of proposed innovations, while martial arts focuses on sensing subtle body motions and quickly reacting to one’s environment. When I first became ...
How to make introductory physics exciting (when you're bored out of your mind)
Why do many students find physics so boring? Cutting-edge physics research gets to address amazing, deep questions: "What is all the stuff in the Universe fundamentally made of?” and “Where did all this stuff come from anyway?” Yet college-level introductory physics courses on Newtonian mechanics can feel quite...mechanical. Why does introductory ...
Introduction to physics: the language of the universe
In elementary and middle school, we learn mathematics for the sake of mathematics, we are never told what mathematics can ultimately be used for or why mathematics is useful other than the fact that it can help us make change and do our taxes one day. What they should be telling you is that the laws of the universe are written in a language that ...
How to solve kinematics problems: a guide to vectors
This article is the third chapter in a series on how to understand and approach kinematics problems. The first chapter covered position, velocity, and acceleration. The second chapter covered solving kinematics in one dimension Now we are going to take a quick detour into vectorland so that we’re ready to approach kinematics in two (and even ...
What is moment and how do you calculate it?
When I tutor my physics students, I want them to understand the fundamentals of the concept, not just how to plug in numbers into an equation. I wished when I was learning physics, my teachers drew upon real life applications more, things we already understand about the world to help us really get it.
How to solve kinematics problems, part 2
This article is the second chapter in a series on how to understand and approach kinematics problems. The first chapter covered position, velocity, and acceleration. Now that we understand these quantities, we are going to use them to solve problems in one dimension.
How to use this guide This blog post is the first in a series on how to understand and approach kinematics problems. It is meant to supplement your class and textbook. I will focus on practical applications, how to solve problems, and common mistakes that students make. If you want to learn the basics of kinematics, I recommend a textbook, but if ...
4 tricks for solving any physics problem
Physics can be intimidating—all those pulleys and protons and projectile motion. If you approach it with the right mindset, however, even the hardest problems are usually easier than you think. When you come up against a tough question, don’t panic. Instead, start with these short, easy tricks to help you work through the problem.
Physics: learn, don’t memorize!
Intro to Physics Blues As a high school student, I took physics my junior year and struggled to stay afloat in the class. While I was interested in understanding and applying the theories I learned, it was difficult to make sense of them in my head. As a result, I began my first collegiate physics course with a lot of excitement, yet some ...
How to use logarithms to simplify Arrhenius temperature dependence
Learning about logarithms is one of those times in math class where you wonder if this will ever be useful in any way. I see lots of students struggle with topics like logs, since they can seem abstract and they aren’t obviously useful. But I’m here to explain why they are actually incredibly important and describe so much of the world we live in! ...
Astronomy vs. physics: two cultural differences
I study solar physics, and many people, often family members, ask me how astronomy and physics differ. Usually, I give the “short answer": that astronomy is just a specific branch of physics. However, there are two major widespread cultural differences that make the “long answer” rather more involved.
Inertia experiments and rolling motion part II
Last time on our physics tutoring blog, we conducted an experiment to investigate the influence of the moment of inertia on rolling motion. We started with two objects that had the same shape, but very different size and mass. Starting from rest, we then set them both rolling down a ramp, to see which one would reach the bottom first. The objects ...
Inertia experiments & rolling motion, part 1
Sometimes, when you are sitting in a physics class staring at an intimidating wall of math, it can be easy to lose sight of the fact that the laws of physics originated as hypotheses to explain observations in the real world. Whether it was Newton getting bopped on the head by an apple, Galileo dropping stuff off the Tower of Pisa, or Franklin ...
3 tricks for physics standardized tests
Learning to take standardized physics exams, like the AP Physics exam or the SAT Physics Subject Test, is not unlike trying to become fluent in a foreign language. Both follow highly idiosyncratic logic and are best learned through practice. (And believe it or not, standardized physics exams have less to do with physics than physics aficionados ...
"Seeing the light" by Jenny Poole
Physics & translational motion
Because MCAT physics often relies on calculation, this part of the physical sciences section of the test often produces an outsize level of anxiety in students. As an MCAT tutor and Physics tutor, I can help you overcome your anxiety around this section of the MCAT. Consider this the first in a series of indeterminate duration and frequency that ...
This week, let’s push a bit beyond the boundaries of standard high school academics and introductory college physics curriculum. Let’s dive into a topic that demonstrates the beauty and occasional counter-intuitive strangeness of modern physics: quantum mechanics! As a physics tutor and enthusiast, I came across this article recently, and thought ...
Welcome back to our series of posts of using our physical intuition in E+M! We’re focusing today on how you can easily intuit the direction of an electric or magnetic field created by some arrangement of charges or magnetic fields. This skill, of looking at a problem and using logic and physical reasoning to figure out with a good deal of ...
Tips from a Physics Tutor: Geometric Intuition, Part I - Vectors
Welcome back to our series of posts on building your physical intuition for E+M! In this series, we’ve looked at some physical reasoning behind Coulomb’s law, imagining point charges as radiating electric field, and saw that the Biot-Savart law gives an analogous result for magnetic fields. We then took the intuition that we’d developed for point ...
The Intuitive Approach: A Personal Story from a Physics Tutor
In these blog posts, I aim to present techniques that will help you generally excel in your physics courses and exams, regardless whether you are taking your first high school physics class or your second semester of graduate-level quantum mechanics. With that goal in mind, we’ve explored ways you can breeze through the math on your homework ...
Physics tutor: doing the experiment - 3 simple rules for uncertainty
Welcome to the last post in our series on experimental error! As a physics tutor, I walk you through the experiental process and explore the traps that might lead you down the wrong path. Over the last several posts, we’ve explored the concepts of accuracy and precision of a measurement, averaging out the noise inherent in your measurement, and ...
Every measurement in your physics experiment will have some noise. How can we measure it, and what can we do to deal with it? Welcome back to the series of posts on experimental error! In the first post, we began to explore some of the ways even a fairly simple experiment is prone to unavoidable experimental error. In this post, we will outline ...
As an overarching theme, I’ve tried to stress that there is more to studying physics than slogging through the math. Instead of treating a problem as a series of dry mathematical manipulations, a sequence of numbers that, when punched into the calculator in the correct order, will yield your answer, we should always try to think about the physical ...
Tips from a Biology Tutor in Cambridge: Taking science tests
We all know that science tests can be challenging. Not only is the content broad and sometimes difficult to master, but the tests themselves can be tricky and confusing. How many of you have run out of time because you got stuck on one confusing question that was probably low yield? Science tests are also notorious for having poorly articulated ...