Physics

Learn about the basic principles that govern the physical world around us. Solid understanding of algebra and a basic understanding of trigonometry necessary.
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Review for AP Physics 1 exam

Studying for the AP Physics 1 exam? Watch these materials to help you review.

One-dimensional motion

In this tutorial we begin to explore ideas of velocity and acceleration. We do exciting things like throw things off cliffs (far safer on paper than in real life) and see how high a ball will fly in the air.

Two-dimensional motion

You understand velocity and acceleration well in one-dimension. Now we can explore scenarios that are even more fun. With a little bit of trigonometry (you might want to review your basic trig, especially what sin and cos are), we can think about whether a baseball can clear the "green monster" at Fenway Park.

Forces and Newton's laws of motion

This is the meat of much of classical physics. We think about what a force is and how Newton changed the world's (and possibly your) view of how reality works.

Centripetal force and gravitation

Learn about centripetal acceleration and centripetal force. Also, learn about the universal law of gravitation and gravitational orbits.

Work and energy

"Energy" is a word that's used a lot. Here, you'll learn about how it's one of the most useful concepts in physics. Along the way, we'll talk about work, kinetic energy, potential energy, conservation of energy, and mechanical advantage.

Impacts and linear momentum

Momentum ties velocity and mass into one quantity. It might not be obvious why this is useful, but momentum has this cool property where the total amount of it never changes. This is called the conservation of momentum, and we can use it to analyze collisions and other interactions. Bam!

Moments, torque, and angular momentum

Everything you've learned about motion, forces, energy, and momentum can be reused to analyze rotating objects. There are some differences, though. Here, you'll learn about rotational motion, moments, torque, and angular momentum.

Oscillations, Mechanical waves, and sound

Waves are responsible for basically every form of communication we use. Whether you're talking out loud, texting on your phone, or waving to someone in a crowd there's going to be a wave transmitting information. Learn about the basics of waves in this topic, then learn more about light waves in the topics below.

Fluids

Atmospheric pressure is like an invisible friend who is always squeezing you with a big hug. Learn more about pressure, buoyant force, and flowing fluid so you can appreciate the sometimes invisible, but crucial, effect they have on us and the world around us.

Thermodynamics

Heat can be useful, but it can also be annoying. Understanding heat and the flow of heat allows us to build heat sinks that prevent our computers from overheating, build better engines, and prevent freeway overpasses from cracking.

Electric charge, electric force, and voltage

Electric forces hold together the atoms and molecules in your eyes which allow you to read this sentence. Take a moment and learn about the force that holds our bodies together.

Circuits

Circuits make computers, digital cameras, and video games possible. Circuits are driving an unprecedented rate of change in how we live. In this topic you'll learn about the physics behind the electronic devices we use.

Magnetic forces, magnetic fields, and Faraday's law

Magnetic fields are extremely useful. The magnetic field of the Earth shields us from harmful radiation from the Sun, magnetic fields allow us to diagnose medical problems using an MRI, and magnetic fields are a key component in generating electrical power in most power plants. In this topic you'll learn about the forces, fields, and laws that makes these and so many other applications possible.

Light waves

Light can seem mysterious. What is light made out of? What causes color? How do 3D movies work? Learn about some of the mysterious properties of light in these tutorials.

Geometric optics

Light waves can be bent and reflected to form new and sometimes altered images. Understanding how light rays can be manipulated allows us to create better contact lenses, fiber optic cables, and high powered telescopes.

Special relativity

Think you know about time and space? Think again. Einstein basically did a pile driver on all our brains when he came up with his theory of special relativity.

Discoveries and projects

Rediscover the most important Scientific observations in a historical progression

Community explanations

Calling great explainers of the world! Help us answer frequently asked physics questions by writing clear, deep, engaging explanations. Your explanation may even be selected for an article on Khan Academy (with full credit to you)!

Ask a Physicist! (archived)

Hi everyone, I'm David, and I love physics. Have a physics question/comment? Ask me anything. I'll be checking the comments section every couple hours until Sunday August 2nd at 12:00 PM PST and replying as often as possible. Also, please feel free to answer other people's questions if you know the answer.
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