Physics
A full year of physics, motion to modern, taught by watching the ball fall, the current flow, and the image flip in a lens.
14 units · 107 topics · 473 questions
The toolkit before the physics starts: how precise a measurement really is, and how a quantity with direction gets added, split, and converted.
Precision and Accuracy in Measurement · Scalars and Vectors · Adding Vectors Graphically · Breaking a Vector into Components · +3 more
Position, velocity, and acceleration, and the graphs that draw the whole story of a moving object without a single equation.
Distance and Displacement · Speed and Velocity · Reading Position-Time Graphs · Reading Velocity-Time Graphs · +3 more
What a curve in the air is actually made of: a horizontal motion and a vertical motion that never touch each other.
The Independence of Horizontal and Vertical Motion · Horizontally Launched Projectiles · Projectiles Launched at an Angle · Range and Maximum Height · +1 more
The three rules that connect force to motion, why surfaces drag on each other, and what a tilted ramp does to both.
Newton's First Law and Inertia · Newton's Second Law · Mass and Weight · Newton's Third Law · +5 more
Why turning is a kind of acceleration, and the one force law that keeps both an apple and the Moon falling.
Uniform Circular Motion · Centripetal Force · Newton's Law of Universal Gravitation · Orbital Motion · +3 more
Energy as the bookkeeping trick that beats tracking every force: how it changes form, gets traded for speed, and gets delivered over time.
Work · Kinetic Energy · Gravitational Potential Energy · Elastic Potential Energy in Springs · +7 more
The quantity that never disappears in a crash: how mass and velocity combine, and what a slow-motion replay shows before and after.
Momentum · Impulse and Change in Momentum · Conservation of Momentum · Elastic Collisions · +2 more
What actually travels when a wave moves: not the water or the rope itself, but a disturbance passed from particle to particle.
What a Wave Actually Is · Transverse and Longitudinal Waves · Wave Speed, Frequency, and Wavelength · Wave Reflection and Superposition · +2 more
Sound as a pressure wave squeezing through the air, and the two tricks — Doppler shift and resonance — that make it change pitch or suddenly get loud.
How Sound Travels · Pitch, Loudness, and the Decibel Scale · The Doppler Effect · Resonance · +3 more
Light bouncing, bending, splitting into color, and bending again through a lens until an image appears somewhere it never physically sits.
The Electromagnetic Spectrum · Reflection of Light · Refraction and Snell's Law · Total Internal Reflection · +7 more
Charge at rest and charge in motion: the force between two charges, and the current, voltage, and resistance that make a circuit actually work.
Static Electricity and Charge · Coulomb's Law · Electric Fields · Electric Current · +7 more
How a moving charge makes a magnetic field, and how a changing magnetic field pushes back and makes a current of its own.
Magnets and Magnetic Fields · Magnetic Force on Moving Charges and Currents · Electromagnetism · Electromagnetic Induction · +2 more
The difference between how hot something is and how much thermal energy it holds, and the three ways heat actually moves from one place to another.
Temperature versus Thermal Energy · Heat Transfer by Conduction · Heat Transfer by Convection · Heat Transfer by Radiation · +3 more
The early-1900s experiments that broke classical physics: particle-like light, atomic fingerprints, decaying nuclei, and bending time.
The Photoelectric Effect · Atomic Spectra and Energy Levels · Radioactive Decay · Half-Life · +3 more