Practice

Mechanics Warmups

Physics is not a discipline, but a way of looking at the world. See if you can use your sense of the world to explain everyday phenomena.

Introduction to Forces

They say you can't go anywhere without forces, and they are right. See if you understand the bread and butter of Newtonian mechanics.

1D Dynamics

A variety of phenomena can be captured by simplistic 1-dimensional models. Learn the essentials of mechanical motion in this stripped-down setting.

2D Dynamics

With 2D dynamics, we can explain the orbit of the planets around the Sun, the grandfather clock, and the perfect angle to throw a snowball to nail your nemesis as they run away from you.

Momentum

From classical mechanics to quantum field theory, momentum is the Universe's preferred language to describe motion. Learn here about momentum, its conservation, and how it captures our intuitions.

Common Misconceptions (Mechanics)

Magazines and common sense are rife with reasonable-sounding, but fundamentally wrong explanations for natural phenomena. Save yourself from embarrassment with these counter-intuitive scenarios.

1D Kinematics

If train A leaves from El Paso at high noon and train B leaves from Dallas at 1 PM, you won't know when they meet unless you master 1D kinematics. What are you waiting for?

Vector Kinematics

If you're in an Airbus 320 cruising at 600 mph, with a 150 mph crosswind, chances are you won't have a strong WiFi signal. Learn vector kinematics now, before you fly.

2D Kinematics

Circular Motion

The wheels on the bus go round and round, but can you name all the forces in a rotating reference frame? Learn to derive these and more through sheer force of reason in Circular Motion.

Kinetic Energy

Energy is the currency of transformation. All systems remain the same unless energy is exchanged between one part and another. Learn here about the energy associated with movement.

Work

Work transfers energy to a system through the forceful manipulation of its state. Do some work on yourself to master this fundamental mode of energy transfer.

Potential Energy

Potential energy lets us do work in the present to change things in the future. If energy is currency, then potential energy is money in the bank.

Conservation of Energy

Energy cannot be created or destroyed in any transformation. This powerful accounting principle helps us analyze everything from particle collisions, to the motion of pendulums.

SI Units

If your friend says they'll meet you 10 minutes down the road, tell them that the SI unit of length is the meter. Learn how scientists make sure to compare apples with apples using the SI system.

Dimensional Analysis

When problems overwhelm our ability to model them, dimensional analysis allows us to cut through the mental block and establish some quantitative insight without thinking.

Fermi Estimation

How many stoplights are in your city? How many golf balls does it take to fill a plane? These seemingly un-answerable questions can be estimated surprisingly accurately using some clever techniques.

Angular Kinematics

If you shrunk to the size of an ant, and were forced to live on the second hand of a wristwatch, it would behoove you to understand movement in a circle. Prepare for the worst with Angular Kinematics.

Torque

From twisting the lid off a jar of olives, to balancing the tandem bicycle you're riding with your parole officer, torque explains it all. Learn to describe and calculate torque, the "twisting force".

Moment of Inertia

A sewer pipe rolls more slowly down an incline than a bowling ball with the same mass. Understand this and more by learning about Moment of Inertia, a measure of how compact objects are.

Rotational Kinetic Energy

Simple Harmonic Motion

A humbling fraction of physics boils down to direct application of simple harmonic motion, the description of oscillating objects. Learn the basis for springs, strings, and quantum fields.

Waves

Waves are disturbances that transport energy without transporting mass. Learn the mechanism underlying sound, deep ocean swells, light, and even the levitation of objects in mid air.

Damped Oscillators

Optics

Bubonic plague drove Isaac Newton to his seminal discoveries on the nature of light in 1665. Make your discoveries without all the hassle in the Optics chapter.

Newton's Law of Gravity

The last of the fundamental forces to evade unification, deep mysteries remain in our understanding of gravity. Get started at the beginning with the Newtonian description of gravity.

Orbits

Believe it or not — the world does not revolve around you. Accept this harsh truth, then calculate the beguiling dance of objects in orbit, from binary stars to the symphony of our Solar System.

Configurational Entropy

Ludwig Boltzmann killed himself so that we could do thermodynamics by enumerating the states of a system. Learn to count, the most important skill in statistical mechanics.

Statistical Thermodynamics

Entropy is the least understood quantity in science, as are the laws that govern it. Avoid the pitfalls and understand entropy better than most working scientists.

Phase Transitions

A sparsely planted forest is likely to have small scale fires while a densely packed one has the potential to burn completely — this shift is called a phase transition.

Quantum Mechanics

According to those who understand quantum mechanics best, there is nobody who understands quantum mechanics. Will you be the first?

Multiparticle Quantum Systems

Quantum particles are weird but multi-particle quantum systems are even weirder. Learn about the incredible phenomena and technology enabled by quantum entanglement.

Relativity and Cosmology

If you stay on Earth while your twin leaves on a galaxy wide quest at half the speed of light, you may have enough time to understand general relativity by the time they get back.

Quantum Mechanical Model

Before the quantum mechanical theory of the hydrogen atom, there was a naïve model that arrived at many of its essential features. Wet your feet with this miraculous triumph of blissful ignorance.

Mathematical Methods and Advanced Topics

Great physicists have a deep mathematical toolbox to draw upon when the going gets tough. Give yourself a chance and pick up some of the essential mathematical methods of physics.