High school physics
Grades 9 to 1217 units and 60 lessons. Helio talks each one through and draws each step on a board.
Units
Motion: position, velocity and acceleration
6 lessons- Position, displacement and velocityLocate an object on an axis, tell displacement from distance and velocity from speed, and read velocity from the slope of a position-time graph.
- AccelerationDefine acceleration as change of velocity per second, decide from the signs of v and a whether an object speeds up or slows down, and draw a motion map.
- Motion graphsRead velocity-time graphs for acceleration from the slope and displacement from the area, and tell what a crossing of two lines means on each kind of graph.
- Constant-acceleration equationsUse v = v₀ + at, Δx = v₀t + ½at², v² = v₀² + 2aΔx and Δx = ½(v₀ + v)t, with signs, to solve straight-line motion, and know when they do not apply.
- Free fallUse a = 9.8 m/s² downward for any object moving only under gravity, solve drops and straight up-and-down throws with signs, and read free-fall data.
- Vectors and projectile motionAdd vectors and split them into components, then treat a projectile's horizontal and vertical motion separately to find fall time, range, maximum height and the state at the top.
Forces and Newton's laws
7 lessons- Forces and free-body diagramsDraw a free-body diagram with one arrow per force, labelled by agent, add the forces along a line to get the net force, and find a normal force that is not equal to the weight.
- Newton's first lawState that an object keeps its velocity unless the net force on it is not zero, show that rest and steady motion are the same balanced case, and explain a sudden stop by inertia.
- Newton's second lawUse a = ΣF/m to find the acceleration from the net force and mass, apply the four-step procedure to a car and an elevator scale, and decide from data whether it supports the law.
- Newton's third lawState that forces come in equal and opposite pairs acting on different objects, name partners as "agent on receiver", and explain why equal forces give unequal accelerations and why pairs never cancel.
- FrictionSeparate static friction, which matches the push up to a maximum, from kinetic friction, f = μN, find N before the friction, and say that friction can point forward.
- Inclined planesTilt the axes along and perpendicular to a slope, split the weight into mg sin θ and mg cos θ, and use them to find the normal force, the acceleration and the angle at which a block slips.
- Circular motionShow that an object moving in a circle at constant speed accelerates toward the centre with a_c = v²/r, find the inward net force F_c = mv²/r, and explain why there is no outward force.
Rotation: torque and equilibrium
1 lesson- Torque and rotational equilibriumUse torque τ = r F sin θ to compare turning effects and apply ΣF = 0 and Στ = 0 to find an unknown distance or support force.
Momentum and collisions
3 lessons- Momentum and impulseCalculate momentum with its sign, connect impulse to the change in momentum, read impulse as the area under a force-time graph, and explain why a longer stopping time means a smaller force.
- Conservation of momentum in collisionsUse a before-and-after table to apply conservation of momentum to one-dimensional collisions, say why it follows from Newton's third law, tell elastic from inelastic collisions by kinetic energy, and handle push-offs.
- Design: reducing force in a collisionPredict the force on an egg from the impulse model, write a design problem as numbered criteria and constraints with a trade-off, and test and refine a design by comparing measured force with the criterion.
Gravity and orbits
2 lessons- Newton's law of universal gravitationUse F = G m₁m₂/r² for the force between two masses, explain the inverse-square pattern, treat the Earth-Moon pull as a third-law pair, and use the field g = GM/r² to explain why astronauts float though gravity has not vanished.
- Kepler's laws and orbitsExplain an orbit as free fall with sideways speed, find the speed and period of a circular orbit from gravity, and use Kepler's laws for the shape, the speed along an ellipse and the period of a planet.
Energy and its conservation
6 lessons- Work and powerCalculate the work of a force with W = F d cos θ, read work as the area under a force-position graph, and use power as work per time.
- Kinetic and potential energyUse K = ½mv², U = mgh and U = ½kx² to find the energy of motion and the energy stored in a gravitational or spring system, and say why potential energy belongs to a system.
- Conservation of energyUse energy bar charts and the equation E_initial + W + Q = E_final to find speeds and thermal energy, and explain that friction changes the form of energy without destroying it.
- Energy at the particle scaleExplain every form of energy as motion or position of particles, tell thermal energy from temperature, and follow a sliding block's energy into the random motion of atoms.
- Design: an energy converterUse efficiency and energy-flow pictures to account for every joule in a converter, compare and chain devices, and improve a wind turbine design by finding its largest loss first.
- Heat, temperature and thermal equilibriumUse Q = mcΔT and the balance of heat lost and gained to find the final temperature of a mixture, and explain why thermal energy flows from hot to cold until the temperatures are equal.
Oscillations: springs and pendulums
2 lessons- Springs and simple harmonic motionUse F = -kx, T = 2π√(m/k) and E = ½kA² to describe a mass on a spring, and explain why the period does not depend on the amplitude.
- Pendulums and resonanceUse T = 2π√(L/g) for a small-angle pendulum, explain why mass and amplitude do not change the period, and explain how pushes at the natural frequency build a large swing.
Fluids: pressure and buoyancy
2 lessons- Pressure and depthUse P = F/A to compare how a force spreads over an area, use P = P₀ + ρgh to find the pressure at a depth in a fluid, and use Pascal's principle to explain how a hydraulic lift multiplies force but not energy.
- Buoyancy and Archimedes' principleExplain the buoyant force as the extra pressure on the bottom of a submerged object, find it with F_B = ρgV, and use it to predict whether an object floats, how much of it is submerged and what a scale reads under water.
Thermodynamics: gases and heat engines
2 lessons- Gas laws and the ideal gasUse P_1 V_1/T_1 = P_2 V_2/T_2 and PV = nRT, with temperatures in kelvin, to predict how the pressure, volume and temperature of a gas change, and explain pressure with moving particles.
- The first law and heat enginesUse ΔU = Q − W, find the work of a gas as the area under a P-V graph, and use e = W/Q_H and the Carnot limit 1 − T_C/T_H to judge a heat engine.
Electricity and magnetism
10 lessons- Electric charge and fieldsExplain charging as the movement of electrons with total charge conserved, say why a charged object attracts a neutral one, and use the electric field E = F/q to find the force on any charge.
- Coulomb's lawUse F = kq₁q₂/r² to find the force between two point charges, predict how it scales with charge and distance, give its direction from the signs, and compare it with gravity.
- Current, voltage, resistance and Ohm's lawDefine current as charge per second and voltage as energy per charge, use V = IR and the I-V graph to find resistance, and say how a wire's length and thickness change its resistance.
- Series and parallel circuitsFind the total resistance, the current and the voltage across each part of series, parallel and mixed circuits, and say why one broken part stops a series string but not a parallel one.
- Electric power and energyUse P = IV and its two other forms, turn watts and hours into kilowatt hours and cost, and explain why a rated bulb changes power at another voltage and why power lines run at high voltage.
- Magnetic fields from currentsDescribe the field of a magnet, show that a current makes a field that circles its wire, find its size with B = μ₀I/(2πr) and B = μ₀nI, and find the force of a field on a current.
- Electromagnetic induction, motors and generatorsShow that a changing magnetic flux induces an emf, find it from ε = N ΔΦ/Δt, give its direction with Lenz's law, and use the idea for generators, motors and transformers without creating any energy.
- Energy stored in fieldsShow that two objects interacting through a field store energy in their arrangement, find it for two point charges and in a uniform field, and tell whether the stored energy rises or falls from the force and the displacement.
- Kirchhoff's rulesUse the junction rule (current in equals current out) and the loop rule (potential changes round a loop add to zero) to find every current in a circuit with two loops.
- CapacitorsUse C = Q/V and C = ε₀A/d, find the energy U = ½CV² stored in a capacitor, combine capacitors in series and parallel, and describe how a capacitor charges through a resistor.
Waves
4 lessons- Wave properties and v = f lambdaSay what a wave carries, measure amplitude, wavelength, period and frequency from graphs, and use v = fλ with the fact that the medium sets the speed.
- Sound and the Doppler effectExplain that sound is a pressure wave that needs a medium, tell pitch from loudness, use an echo to find a distance, and explain why a moving source shifts the frequency you hear.
- Reflection and refractionUse the normal to apply the law of reflection and Snell's law, explain refraction by the change of speed, and find when total internal reflection happens.
- Interference, diffraction and standing wavesAdd waves by superposition, decide loud or quiet from a path difference, say when a wave spreads through a gap, and find the frequencies of a string and a pipe.
Optics: mirrors and lenses
2 lessons- Mirrors and ray diagramsLocate the image in a plane, concave or convex mirror with the principal rays and the mirror equation 1/f = 1/d_o + 1/d_i, and describe it as real or virtual, upright or inverted, larger or smaller.
- Lenses and the thin lens equationLocate the image formed by a converging or diverging lens with the principal rays and 1/f = 1/d_o + 1/d_i, and say whether it is real or virtual, upright or inverted, larger or smaller.
Electromagnetic radiation and information
5 lessons- Digital informationSay how a wave becomes a list of numbers by sampling, find the size of a digital file, explain why a threshold removes noise, and weigh claims about digital storage.
- The EM spectrumExplain that light, radio and X-rays are one family of waves that need no medium, order the spectrum by wavelength, use c = fλ, and link photon energy to wavelength.
- Light as particle: the photoelectric effectShow how the photoelectric effect contradicts the wave model of light, use Kmax = hf − φ with a work function, and say why light needs both wave and photon models.
- EM radiation and living tissueCompare a photon's energy with the 4 to 10 eV of a chemical bond to tell ionizing from non-ionizing radiation, separate photon damage from heating, and evaluate a claim about radiation.
- Technologies that use wavesExplain how ultrasound, optical fibres, radio and solar cells each use one wave behaviour, with checks from echo timing, critical angles and panel power.
Nuclear physics
2 lessons- Radioactive decay and half-lifeBalance alpha and beta decay equations by conserving A and Z, say which radiation is stopped by what, and use the half-life to find how much of a sample is left.
- Fission, fusion and E = mc^2Use the binding energy per nucleon curve to say why fission and fusion release energy, count nucleons in both, and find the energy from the mass lost with E = Δm c².
Special relativity
1 lesson- Special relativity: time dilation and length contractionUse the constant speed of light to explain why moving clocks run slow and moving lengths shrink, and calculate Δt = γΔt₀ and L = L₀/γ at 0.60c, 0.80c and 0.98c.
Stars and the universe
3 lessons- The Sun: fusion and its life cycleExplain that fusion of hydrogen into helium powers the Sun, find its power and the mass it converts each second, trace how its energy reaches us, and describe its life cycle from the evidence.
- Evidence for the Big BangRead a redshift, use Hubble's law to find a galaxy's speed and distance and a rough age of the universe, and name three lines of evidence that each test a prediction of the Big Bang theory.
- Nucleosynthesis in starsSay how stars make elements from hydrogen up to iron, why fusion stops at iron, how supernovae scatter the elements, and how a star's mass sets how far it goes.
Plate tectonics
2 lessons- Plate motion and landformsDescribe the three kinds of plate boundary and the landforms at each, use the evidence of seafloor ages, magnetic stripes and hot-spot chains, and use rate = distance / time to show that a few cm/yr builds oceans.
- Earth's interior and mantle convectionUse seismic waves to describe the layers of the Earth, find the distance to an earthquake from the gap between P and S waves, and explain how heat drives slow mantle convection that moves the plates.