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Play with Physics

Touch it. Watch the numbers move. Read the law.

Every law of physics as something you can drag — the scene, the live values and the formula move together. Classes 6 to 10, built lesson by lesson.

All 174 Play With Physics lessons

Every lesson in the series, by class. Every lesson is free to play once you sign in.

Class 6

  • Everything is Stuff — Solids, liquids and gases — three dances of the same dots · Matter
  • Stuff Changes Costume — Melting, freezing, evaporating — matter's quick changes · Matter
  • Whose Hand? — Why the world needed standard units · Physical Quantities and Measurement
  • The Right Tool for the Job — Rulers, tapes, balances, clocks — measuring like a scientist · Physical Quantities and Measurement
  • Push and Pull — What forces do — move, stop, turn, squash · Force
  • Force Families — Muscular, magnetic, gravitational, frictional · Force
  • The Gripping Force — Friction — the force that rubs both ways · Force
  • Clever, Not Strong — What machines really do for us · Simple Machines
  • The Magic Plank — Levers — a rod, a pivot, and suddenly you're strong · Simple Machines
  • Rope Tricks — Pulleys — change the direction, share the load · Simple Machines
  • The Lazy Slope — The inclined plane — and its cousins, the wedge and the screw · Simple Machines
  • Light Walks Straight — Rectilinear propagation — and the shadows that prove it · Light
  • A Camera with No Lens — The pinhole camera — straight lines make pictures · Light
  • The Choosy Stone — Magnets and what they attract · Magnetism
  • Make a Magnet — From plain nail to magnet — and back again · Magnetism
  • The Earth Whisperer — The compass — a magnet that always knows north · Magnetism

Class 7

  • How Much Space? — Measuring volume — even of a lumpy stone · Physical Quantities and Measurement
  • Packed Tight or Loose? — Density — why iron sinks and wood floats · Physical Quantities and Measurement
  • Ways of Moving — Slide, spin, swing — the kinds of motion · Motion
  • Steady or Not? — Uniform motion, speed — and two trains to compare · Motion
  • The Mixed Journey — Distance vs the shortcut home · Motion
  • Stored and Moving — The two forms of mechanical energy · Energy
  • Energy Swaps Costumes — Conversions — and the total that never changes · Energy
  • The Perfect Bounce — Reflection — light's unbreakable rule · Light Energy
  • Your Backwards Twin — The plane mirror image and its flipped writing · Light Energy
  • Mixing Light — Red, green, blue — and why an apple needs red light to be red · Light Energy
  • Hot is Not Heat — Temperature, thermometers — and the lake that beats the teaspoon · Heat
  • Pass It or Block It — Conductors and insulators of heat · Heat
  • Three Roads for Heat — Conduction, convection, radiation · Heat
  • Black, White, Shiny — Absorbers, reflectors — and the thermos that knows all three roads · Heat
  • Everything That Sounds, Trembles — Vibrations — where every sound is born · Sound
  • Sound Needs a Messenger — The bell in the jar — no air, no sound · Sound
  • The Loop Rule — Circuits, conductors — and why the gap kills the glow · Electricity and Magnetism
  • Battery Language — Cells, torches and circuit symbols · Electricity and Magnetism
  • The Sure Test — Magnets: poles, repulsion and the invisible field · Electricity and Magnetism
  • The Magnet with a Switch — Electromagnets and the electric bell · Electricity and Magnetism

Class 8

  • The Particle Dance — Solid, liquid, gas — one box, three arrangements · Matter
  • The Great Escape — Melting, boiling, condensing — matter changes costume · Matter
  • The Vanishing Puddle — Evaporation — the quiet escape from the surface · Matter
  • How Crowded is Matter? — Density — measure, divide, identify · Physical Quantities and Measurement
  • Weigh It Underwater — The water test — density without a ruler · Physical Quantities and Measurement
  • The Float Rule — Density decides destiny — sink or swim · Physical Quantities and Measurement
  • The Turning Effect — Moment of force — the door-handle secret · Force and Pressure
  • The Pressure Point — P = F/A — sharp knives and wide straps · Force and Pressure
  • Deep Water Presses — Liquid pressure grows with depth · Force and Pressure
  • The Sky Presses — Atmospheric pressure — living at the bottom of an air ocean · Force and Pressure
  • Work Means Move — W = F × d — no motion, no work · Energy
  • Two Piggy Banks — Potential and kinetic energy · Energy
  • Energy Never Dies — Conversion and conservation — the pendulum's oath · Energy
  • The Bending Trick — Refraction — light changes lanes at every border · Light Energy
  • Shallow Lies — Bent sticks, lifted coins — refraction's illusions · Light Energy
  • The Curved Mirror — Meet the concave mirror: P, F and C · Light Energy
  • Images on the Axis — Slide the candle — the concave mirror answers · Light Energy
  • The Hidden Rainbow — Dispersion — white light was seven colours all along · Light Energy
  • Heat Changes Things — Expansion — matter needs room when warm · Heat Transfer
  • Density Shifts — Warm rises, cold sinks — and water's famous exception · Heat Transfer
  • Quiet vs Violent — Evaporation and boiling — the molecular story · Heat Transfer
  • Picture of a Sound — Amplitude, frequency, time period — reading the wave · Sound
  • High or Loud? — Pitch vs loudness — and a string to prove it · Sound
  • The Clingy Balloon — Static electricity — charges that sit still · Electricity
  • Power Reaches Home — From the generating station to your three wires · Electricity
  • The Meter Counts — Electrical energy, power and the units you pay for · Electricity
  • The Weakest Link — Fuses and safety — electricity's bodyguards · Electricity

Class 9

  • Why Units Rule — A number without a unit is a rumour · Measurements and Experimentation
  • Small, Smaller, Smallest — The length ladder — from femtometre to light year · Measurements and Experimentation
  • The Vernier Trick — Reading BETWEEN the millimetre marks · Measurements and Experimentation
  • One Hundredth of a Millimetre — The screw gauge — precision by rotation · Measurements and Experimentation
  • The Swinging Clock — The simple pendulum — and what the bob's mass does NOT do · Measurements and Experimentation
  • Moving or Not? — Rest, motion, and the six quantities that rule them · Motion in One Dimension
  • Path vs Shortcut — Distance and displacement — the odometer and the crow · Motion in One Dimension
  • How Fast, Which Way — Speed vs velocity — one number, two meanings · Motion in One Dimension
  • Speeding Up, Slowing Down — Acceleration, retardation and gravity's metronome · Motion in One Dimension
  • The Story in the Graph — s–t and v–t: slope and area tell everything · Motion in One Dimension
  • Three Golden Equations — v = u + at and friends — now stop the car · Motion in One Dimension
  • The Force Family — Contact and non-contact — how pushes reach things · Laws of Motion
  • The Lazy Universe — Newton's first law — inertia and the myth of the stored push · Laws of Motion
  • Momentum Matters — p = mv — mass in motion · Laws of Motion
  • F = ma — Newton's second law — the equation that runs the world · Laws of Motion
  • The Equal & Opposite Trap — Newton's third law — why the pairs never cancel · Laws of Motion
  • Gravity's Long Reach — Universal gravitation — mass vs weight, planet by planet · Laws of Motion
  • The Point of Pressure — P = F/A — why camels laugh at sand · Pressure in Fluids and Atmospheric Pressure
  • Deeper is Harder — Liquid pressure: P = hρg and the three-hole bottle · Pressure in Fluids and Atmospheric Pressure
  • Pascal's Superpower — Transmit the pressure, multiply the force · Pressure in Fluids and Atmospheric Pressure
  • The Ocean of Air — Atmospheric pressure — the crush you never feel · Pressure in Fluids and Atmospheric Pressure
  • Reading the Sky — Barometers — altitude, weather and 76 cm of mercury · Pressure in Fluids and Atmospheric Pressure
  • The Water Pushes Back — Upthrust — the force you feel in every pool · Upthrust in Fluids, Archimedes' Principle and Floatation
  • Eureka! — Archimedes catches a goldsmith — with bathwater · Upthrust in Fluids, Archimedes' Principle and Floatation
  • Dense Sense — Density and relative density — naming metals with a ratio · Upthrust in Fluids, Archimedes' Principle and Floatation
  • Float or Sink? — The principle of floatation — why iron ships don't drown · Upthrust in Fluids, Archimedes' Principle and Floatation
  • Floatation at Work — Submarines, icebergs, hydrometers — the principle employed · Upthrust in Fluids, Archimedes' Principle and Floatation
  • Heat is Motion — The kinetic story — and why the rails need a gap · Heat and Energy
  • Water Breaks the Rules — Anomalous expansion — the 4 °C secret that saves the fish · Heat and Energy
  • Energy Everywhere — Sources of energy — the renewable and the running-out · Heat and Energy
  • Downhill Energy — Degradation — every conversion pays a heat tax · Heat and Energy
  • The Warming Blanket — Greenhouse effect and global warming — the physics of the headline · Heat and Energy
  • The Law of the Bounce — ∠i = ∠r — and the 2θ mirror trick · Reflection of Light
  • Through the Looking Glass — The plane-mirror image — your equidistant, flipped twin · Reflection of Light
  • Hall of Mirrors — Two mirrors, an angle, and n = 360/θ − 1 · Reflection of Light
  • Curved Mirrors — P, F, C — the anatomy of a spherical mirror · Reflection of Light
  • Ray Diagrams that Work — The concave mirror image walk · Reflection of Light
  • Mirrors with Jobs — Concave or convex? Match the mirror to the mission · Reflection of Light
  • Everything that Sounds, Shakes — Sound is born from vibration and travels as a longitudinal wave · Propagation of Sound Waves
  • No Air, No Noise — The bell-jar experiment — sound needs a medium · Propagation of Sound Waves
  • What Changes the Speed — Temperature yes, humidity yes, pressure NO · Propagation of Sound Waves
  • Below and Beyond Hearing — Infrasound, ultrasound and the 20–20,000 window · Propagation of Sound Waves
  • The First Circuit — A loop, a switch, a bulb — the whole idea of electricity · Current Electricity
  • Speak Circuit — Symbols and diagrams — electricity's written language · Current Electricity
  • Which Way Does It Flow? — Conventional current vs the electrons' actual march · Current Electricity
  • Watts Wisely — Efficient use of energy — the bill as a physics exam · Current Electricity
  • The Reach of a Magnet — Induced magnetism — the nail that becomes a magnet · Magnetism
  • Invisible Lines — Field lines — mapping the magnet's territory · Magnetism
  • Earth, the Giant Magnet — Neutral points — where two fields cancel to zero · Magnetism
  • Magnets on Demand — The electromagnet — revision with a junkyard crane · Magnetism

Class 10

  • The Charge Parade — What actually flows in a wire — and how fast is a "lot"? · Current Electricity
  • Push of a Cell — e.m.f., terminal voltage and the volts that vanish inside · Current Electricity
  • Ohm's Playground — One straight line, one bent one — and the law between them · Current Electricity
  • Resistance Recipe — Length, thickness, material, heat — cook any resistance you want · Current Electricity
  • Split or Stack — Series vs parallel — and the current that never gets used up · Current Electricity
  • Watt's the Cost — Power, energy and the electricity bill you can now out-think · Current Electricity
  • Chapter Boss: Circuit Master — Everything from charge to the bill — prove the chapter is yours · Current Electricity
  • The Bending Ray — Snell's law — why light kinks at every surface · Refraction of Light at Plane Surfaces
  • Deeper than it Looks — Real depth, apparent depth, and the coin that floats up · Refraction of Light at Plane Surfaces
  • Through the Prism — Deviation, and the hunt for its minimum · Refraction of Light at Plane Surfaces
  • The Escape Angle — Critical angle — where refraction dies and reflection takes over · Refraction of Light at Plane Surfaces
  • Trapped Light — Put total internal reflection to work: the prism periscope · Refraction of Light at Plane Surfaces
  • Meet the Lens — Convex gathers, concave scatters — watch a parallel beam decide · Refraction through a Lens
  • Three Magic Rays — The only three rays you ever need to draw · Refraction through a Lens
  • The Image Walk — Drag the object from infinity to inside F — the whole chapter in one slider · Refraction through a Lens
  • Sign of the Times — The lens formula with its signs — where the numbers come from · Refraction through a Lens
  • Pocket Microscope — The magnifying glass — one lens, held exactly right · Refraction through a Lens
  • Slide vs Spin — One box, one push — two completely different motions · Force
  • The Turning Trick — Moment of force: why the spanner beats the fist · Force
  • The Couple — Two forces, zero push, pure turn · Force
  • Perfect Balance — The principle of moments — earn your equilibrium · Force
  • The Balancing Point & the Whirl — Centre of gravity, toppling — and the force that isn't there · Force
  • Work is Sneaky — W = FS cos θ — and the pull that does nothing · Work, Energy and Power
  • The Rate Race — Power: same work, different hurry · Work, Energy and Power
  • Energy the Shape-Shifter — Forms of energy and the chains between them · Work, Energy and Power
  • Stored vs Moving — Potential and kinetic — energy's two bank accounts · Work, Energy and Power
  • Nothing is Lost — Conservation of energy — the pendulum's promise · Work, Energy and Power
  • Chapter Boss: Loop Designer — Spend height like money — the conservation final · Work, Energy and Power
  • Why Machines? — MA, VR, efficiency — and the cheat that never works · Machines
  • Lever Law — Class I: the crowbar and its arms · Machines
  • Levers Everywhere — Class II, class III — and the levers in your own arm · Machines
  • The Pulley Puzzle — Fixed, movable, block & tackle — count the ropes · Machines
  • Chapter Boss: Machine Shop — Cheapest rig that survives — the contractor's final · Machines
  • The Deviation Dial — Why violet always loses the race through glass · Spectrum
  • Rainbow Factory — Dispersion, VIBGYOR, and Newton's second prism · Spectrum
  • Beyond the Rainbow — The electromagnetic spectrum: seven waves, one family · Spectrum
  • Why is the Sky Blue? — Scattering — the answer every child deserves · Spectrum
  • Bounce that Sound — Reflection of sound obeys light's rules · Sound
  • Echo Ranger — The 17-metre rule and measuring by ear · Sound
  • Everything has a Note — Natural vibrations — and the knobs that tune them · Sound
  • The Resonance Trap — When the push arrives exactly on time · Sound
  • Loud, High, Sweet — Loudness, pitch, quality — reading the waveform · Sound
  • Power Comes Home — From the station to your socket — why the volts climb before they fall · Household Circuits
  • Ring Around the House — Why every room is wired in parallel · Household Circuits
  • The Sacrificial Wire — Fuses and MCBs — the weakest link, on purpose · Household Circuits
  • Earth Saves — The third pin — a wire you hope never works · Household Circuits
  • The Compass Flinch — Oersted's accident — currents make magnetic fields · Electro-magnetism
  • Build an Electromagnet — Turns, current, core — a magnet with an OFF switch · Electro-magnetism
  • The Invisible Push — Force on a current in a field — Fleming's left hand · Electro-magnetism
  • Spin It: the DC Motor — Why the split ring is the whole invention · Electro-magnetism
  • Motion Makes Current — Faraday, Lenz, and the current that only exists while things CHANGE · Electro-magnetism
  • Voltage Elevator — The transformer — a.c.'s greatest trick · Electro-magnetism
  • Heat ≠ Hot — A cold lake outguns a boiling spoon · Calorimetry
  • Thermal Appetite — Specific heat capacity — why water tames climates · Calorimetry
  • The Mixing Court — Method of mixtures — heat lost equals heat gained · Calorimetry
  • The Plateau Mystery — Heating curves — where the thermometer stops and the state changes · Calorimetry
  • Hidden Heat — Latent heat — the 336 J/g nobody sees on a thermometer · Calorimetry
  • Inside the Nucleus — Protons, neutrons, isotopes — the atom's tiny heart · Radioactivity
  • The Three Rays — α, β, γ — three personalities from one unstable heart · Radioactivity
  • Nuclear Bookkeeping — Decay equations — A and Z must always balance · Radioactivity
  • Half-Life & Heavy Choices — Randomness with a rhythm — and what we owe the atom · Radioactivity
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