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Physics

Motion, forces, energy, waves, light, electricity and the modern physics that explains the universe.

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Physics on LearnViz HighSchoolEdu has 150 interactive topics. Each one has a plain-English explanation, a live animation you can control, key ideas to remember and a quick quiz. The same laws describe car crashes, sports, satellites and everyday machines.

Motion

1Scalars and VectorsScalars have size only; vectors have size and direction.2Distance and DisplacementDistance is the path length; displacement is the straight-line change in position.3Speed and VelocitySpeed is how fast; velocity is how fast and in which direction.4AccelerationAcceleration is the rate of change of velocity.5Position–Time GraphsThe slope of a position–time graph is velocity.6Velocity–Time GraphsSlope gives acceleration and area gives displacement.7Equations of MotionFour equations link displacement, velocity, acceleration and time for constant acceleration.8Free FallWithout air resistance, all objects fall with the same acceleration.9Projectile MotionA projectile has constant horizontal velocity and accelerates down vertically.10Relative MotionVelocity depends on the observer's frame of reference.11Uniform Circular MotionCircular motion at constant speed still has acceleration toward the center.12Frames of ReferenceChoosing a frame simplifies a physics problem.13Average vs Instantaneous VelocityInstantaneous velocity is the slope at a single moment.14Terminal VelocityAir resistance balances weight, so falling speed levels off.15Motion Graph InterpretationReading graphs is the key skill for kinematics.16Reaction Time and Stopping DistanceStopping distance = reaction distance + braking distance.17Vertical ThrowAn object thrown up slows, stops, then falls.18Displacement on a PlaneCombine x and y displacements with vectors.19Speed of Sound and Light in Motion ProblemsCompare very fast signals to everyday speeds.20Dimensions and UnitsEvery physical quantity has a unit; SI units form a common system.

Forces

21Force and Newton's First LawAn object stays at rest or in constant motion unless a net force acts.22Newton's Second LawNet force equals mass times acceleration: F = ma.23Newton's Third LawForces come in equal and opposite pairs acting on different objects.24Mass vs WeightMass is the amount of matter; weight is the gravitational force on it.25Free-Body DiagramsA free-body diagram shows every force acting on one object.26Normal Force and TensionContact forces push perpendicular to surfaces and pull along ropes.27FrictionFriction opposes sliding between surfaces.28Inclined PlanesOn a slope, weight splits into components along and perpendicular to the surface.29Air Resistance and DragMoving through fluid creates a force opposing motion.30Springs and Hooke's LawA spring's restoring force is proportional to its stretch.31EquilibriumNet force and net torque are both zero in equilibrium.32Torque and MomentsTorque measures a force's turning effect: τ = rF sin θ.33Center of MassThe point where an object's mass acts as if concentrated.34PressurePressure is force per unit area.35Newton's Law in ElevatorsApparent weight changes with acceleration.36Hooke's Law ExperimentMeasure stretch against load to find the spring constant.37Centripetal ForceThe net inward force that keeps an object on a circular path.38Drag Racing and TractionTraction limits how fast a car can accelerate.

Work, Energy and Momentum

39WorkWork is force times distance in the direction of the force.40Kinetic EnergyThe energy of motion: ½mv².41Gravitational Potential EnergyEnergy stored by height in a gravitational field: mgh.42Conservation of EnergyEnergy cannot be created or destroyed, only transformed.43PowerPower is the rate of doing work: P = W/t.44EfficiencyEfficiency compares useful output to total input.45Simple MachinesLevers, pulleys and ramps trade force for distance.46Elastic Potential EnergyA stretched spring stores energy: ½kx².47Work–Energy TheoremNet work done equals the change in kinetic energy.48Linear MomentumMomentum is mass times velocity: p = mv.49ImpulseImpulse is force over time and equals the change in momentum.50Conservation of MomentumIn an isolated system, total momentum stays constant.51Elastic and Inelastic CollisionsElastic collisions conserve kinetic energy; inelastic ones don't.52Collisions in Two DimensionsConserve momentum separately in x and y.53Rockets and PropulsionRockets accelerate by throwing mass backward.54Energy ResourcesSources of energy are renewable or non-renewable.

Circular Motion and Gravity

55Angular VelocityAngular velocity measures how fast an angle changes.56Newton's Law of GravitationEvery two masses attract with a force F = Gm₁m₂/r².57Gravitational Field StrengthField strength g = GM/r² at distance r from a mass.58Orbits and SatellitesSatellites fall around Earth while moving sideways fast enough to miss it.59Kepler's LawsPlanets move on ellipses, sweep equal areas in equal times, and obey T² ∝ a³.60Escape VelocityThe minimum speed to escape a planet's gravity.61Gravitational Potential Energy in SpaceU = −GMm/r is zero at infinity and negative closer in.62TidesTides come from differences in the Moon's pull across Earth.63WeightlessnessAstronauts feel weightless because they are in free fall.64Banked CurvesBanking uses the normal force to supply centripetal force.65Rotational KinematicsRotation obeys equations like linear motion.66Moment of Inertia and Angular MomentumRotational inertia and angular momentum are the spinning analogues of mass and momentum.

Fluids

67DensityDensity is mass per volume: ρ = m/V.68Pressure in FluidsPressure increases with depth: P = ρgh.69Buoyancy and Archimedes' PrincipleThe buoyant force equals the weight of fluid displaced.70Pascal's PrinciplePressure applied to a fluid is transmitted everywhere in it.71Bernoulli's PrincipleFaster fluid flow means lower pressure.72Atmospheric PressureThe weight of air above us produces pressure of about 101 kPa.

Thermal Physics

73Temperature and HeatTemperature measures average particle energy; heat is energy transferred.74Temperature ScalesCelsius, Fahrenheit and Kelvin measure temperature.75Specific Heat CapacityThe energy to raise 1 kg by 1 °C: Q = mcΔT.76Thermal ExpansionMost materials expand when heated.77Conduction, Convection and RadiationHeat moves by contact, fluid flow and electromagnetic waves.78Change of StateSubstances melt, boil, freeze or condense when energy is added or removed.79Kinetic Theory of GasesGas pressure comes from particles hitting walls.80Ideal Gas LawPV = nRT links pressure, volume, temperature and amount of gas.81First Law of ThermodynamicsEnergy is conserved: ΔU = Q − W.82Second Law and EntropyEntropy of an isolated system never decreases.83Heat EnginesEngines convert heat into work by cycling a gas.84CalorimetryMeasure heat by mixing substances and tracking temperature.85Greenhouse EffectGases trap infrared radiation, keeping Earth warm.86Absolute Zero and Low TemperatureAt 0 K particles have minimum energy.

Waves and Sound

87Wave BasicsWaves transfer energy without transferring matter.88Transverse and Longitudinal WavesParticles move perpendicular or parallel to the wave direction.89Frequency and PeriodFrequency is cycles per second; period is the time per cycle.90Superposition and InterferenceOverlapping waves add together.91Standing WavesWaves trapped between boundaries form nodes and antinodes.92Sound WavesSound is a pressure wave through matter.93Pitch, Loudness and TimbreFrequency sets pitch, amplitude sets loudness, harmonics set timbre.94Doppler EffectMotion of source or observer shifts perceived frequency.95ResonanceDriving a system at its natural frequency produces large oscillations.96Reflection and EchoesWaves bounce off surfaces.97Refraction of WavesWaves change speed and bend across boundaries.98DiffractionWaves spread when passing gaps or edges.99BeatsTwo close frequencies produce a throbbing sound.100UltrasoundSound above 20 kHz is used in medicine and industry.

Light and Optics

101Electromagnetic SpectrumLight is one band of electromagnetic waves ordered by frequency.102Speed of LightLight travels at c ≈ 3 × 10⁸ m/s, the cosmic speed limit.103Reflection of LightA mirror sends light back at the same angle.104Refraction and Snell's LawLight bends when entering a new medium: n₁ sin θ₁ = n₂ sin θ₂.105Total Internal ReflectionBeyond the critical angle, light cannot leave the denser medium.106LensesConverging lenses focus light; diverging lenses spread it.107Mirrors and Image FormationCurved mirrors form real or virtual images.108The Human EyeThe eye focuses light on the retina with a flexible lens.109Colour and DispersionWhite light splits into colours because each bends differently.110Primary Colours and Colour MixingLight mixes additively; pigments mix subtractively.111Interference of LightLight waves interfere to make bright and dark fringes.112PolarizationPolarized light oscillates in a single plane.113Telescopes and MicroscopesCombinations of lenses extend our vision.114Photoelectric EffectLight can knock electrons out of metal, but only if its frequency is high enough.

Electricity

115Electric ChargeCharge is a property of matter; like charges repel and unlike attract.116Coulomb's LawElectric force follows an inverse-square law: F = kq₁q₂/r².117Electric FieldsA field is the force per unit charge at a point.118Electric Potential and VoltageVoltage is the energy per unit charge.119CurrentCurrent is the flow of charge: I = Q/t.120Resistance and Ohm's LawV = IR links voltage, current and resistance.121Series CircuitsComponents in series share one path.122Parallel CircuitsParallel branches share the same voltage.123Electrical Power and EnergyPower P = VI and energy E = Pt.124CapacitorsCapacitors store charge in an electric field.125Kirchhoff's LawsCurrent in equals current out; voltages around a loop sum to zero.126Electric SafetyFuses, earthing and insulation protect people from shocks.127Static ElectricityRubbing transfers electrons and builds up static charge.128Conductors and InsulatorsConductors let charge flow; insulators resist it.129Batteries and CellsChemical reactions push charge around a circuit.130Household ElectricityAC mains alternate direction many times per second.

Magnetism

131Magnets and Magnetic FieldsMagnets have two poles; field lines run from north to south.132ElectromagnetismMoving charges create magnetic fields.133Magnetic Force on Charges and WiresA magnetic field pushes moving charges sideways.134Electromagnetic InductionA changing magnetic field induces voltage.135Generators and MotorsGenerators turn motion into electricity; motors do the reverse.136TransformersTransformers change AC voltage using coils.137Earth's Magnetic FieldEarth's field shields us and guides compasses.138Electromagnetic WavesChanging electric and magnetic fields propagate as waves.

Modern Physics

139Atomic StructureAtoms have a dense nucleus and orbiting electrons.140RadioactivityUnstable nuclei emit alpha, beta or gamma radiation.141Half-LifeThe time for half of a radioactive sample to decay.142Nuclear Fission and FusionSplitting heavy nuclei or joining light ones releases energy.143Special RelativitySpace and time depend on relative motion near light speed.144Mass–Energy EquivalenceE = mc² connects mass and energy.145Wave–Particle DualityLight and matter show both wave and particle behavior.146Quantum Energy LevelsElectrons in atoms occupy discrete energy levels.147Uncertainty PrincipleYou can't know position and momentum exactly at once.148Particle PhysicsMatter is built from quarks and leptons with force-carrying bosons.149Big Bang and CosmologyThe universe began hot and dense about 13.8 billion years ago and keeps expanding.150Stars and Stellar EvolutionStars live by fusion and end as white dwarfs, neutron stars or black holes.

Frequently asked questions

What topics are in Physics?

There are 150 topics, including Scalars and Vectors, Distance and Displacement, Speed and Velocity, Acceleration, Position–Time Graphs, and more.

Who is Physics on LearnViz for?

High school students who want to understand physics visually, teachers who want a quick classroom demonstration, and parents helping with homework.

Do I have to study the topics in order?

No. The list follows the order of the course, but every topic has its own page, so you can start wherever you need help.

How do I track my progress?

Open a topic and press “Mark as learned”. This subject page then shows how many topics you have completed. Progress is saved in your own browser.

How is Physics used in real life?

The same laws describe car crashes, sports, satellites and everyday machines.