physics
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Ptolemy, the Alexandrian polymath, proposed a model of the universe as a series of concentric spheres. The Earth was the central sphere1 with the sun and stars existing on spheres farther from the center. This is known as a geocentric model, and it was designed to explain the motion of heavenly bodies in the night sky. It was the dominant idea in ...
The discovery of radioactivity revolutionized physics. What started as a study of phosphorescent materials in a Paris laboratory quickly grew to define a new area of physics, one that is vital to medicine, environmental studies, and national defense.
Starting out in physics and astronomy can seem overwhelming due to the large amount of different topics covered in introductory courses. Sometimes it seems like every week we have a whole new list of equations to use in our homework. In many academic areas memorizing equations, like the Pythagorean theorem, is very useful for problem solving (and ...
You are Patrick Mahomes, the quarter back for Kansas City in the National Football League. You are centered horizontally on the field and 3 meters behind the line of scrimmage with the ball in your hand, and you need to throw the ball to Travis Kelce, who is 7 meters ahead of the line of scrimmage and 8 meters to your left. Travis is running ...
In my experience as an instructor and teaching assistant at the University of Washington, I have worked with many students who are biology or chemistry majors desperately trying to stay afloat in introductory physics. They describe the experience as a painful one and feel their hard work does not pay off. If you feel similarly, the good news is ...
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.
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 ...
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.
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 ...
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 ...
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 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 ...
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.
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 ...
“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. ...
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.
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.
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 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.
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 ...
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 ...
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?”
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.
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 ...
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 ...
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 ...
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 ...
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 ...