Real numerical simulations you can nudge and watch respond — a spring-mass system across every damping regime, pendulums from predictable to chaotic, ballistics that carry their own drag, and orbits worked from Newton upwards. Beverage Cooling solves the same heat equation as the Steak Timer and the Egg Timer: same physics, different object. A can in a fridge, a steak in an oven and an egg in boiling water differ only in their boundary condition and what they are made of.
A second-order system across all four damping regimes — set the mass, spring and damping, and watch the step response ring, settle, or crawl.
Seventeen decades from radio to gamma, with wavelength, frequency and photon energy moving together — visible light in true colour and a Planck curve for any temperature.
See the field of a magnet, a wire or a coil, what it does to a moving charge and a current, how a changing field makes a voltage, and the Earth’s field and compass at your city.
Fly anything from a bullet to Concorde: the speed of sound at any height, the Mach cone and its shock, when the boom reaches the ground — and why some never do. With a flyby you can hear.
A live flow simulation around a wing: angle of attack, slat, flap, spoiler, flow separation and shock waves from low speed to Mach 3.
Heat anything and it glows. Set a temperature and see its colour, its spectrum, how much of the power is light, and how fast it loses energy.
Watch a sample decay atom by atom, see the half-life curve appear, work out an age from what is left and find how active a quantity of material is.
Watch two waves add, cancel, beat and freeze into a standing wave; find the notes a string or pipe can make, and shake it at any frequency to see resonance.
Move an object in front of a lens or mirror and see the rays, where the image forms, whether it is real or virtual, upright or upside down, and how big it is.
Near and far limits, hyperfocal distance, and the aperture past which diffraction costs more than stopping down buys — plus why the focal length barely matters at the same framing.
Snell's law, critical angle and Fresnel reflection with a live ray diagram, plus single-slit, double-slit, grating and Airy-disc patterns drawn out.
The same Lagrangian mechanics, one, two, or three links deep — from a clean predictable swing to full chaotic motion.
A block on a slope, simulated with real friction — set the angle and coefficients and watch whether it holds, slides, or slides back.
A real 2D transient heat-transfer simulation — watch a can or bottle actually cool, with live convection and radiation physics.
The energy to warm, melt or boil anything, what happens when hot and cold are mixed, how heat goes through a wall, and how long a hot thing takes to cool by convection and radiation.
The classic no-drag trajectory, plus a real 3D drag + Magnus-lift golf simulator — clubs, wind, world gravity, bounce and roll.
Race two falling objects with real drag physics — recreate Apollo 15's hammer-and-feather drop on the Moon.
Enter any three of s, u, v, a and t and get the other two, with the equation used and the working shown.
Built from one fact: everybody measures light at the same speed. Watch a light clock slow down, see why “now” is not universal, and find the 38 microseconds a day that satellite navigation depends on.
The sky above any place at any moment — which constellations are up, how high, and which way to look. Run the night forward and watch it turn, and find out why it all arrives four minutes early.
Every planet in 3D, drawn from its real orbital elements — at true scale, where they all but vanish, and compressed, where you can see them. Size against size, and a head-to-head on ten measures.
Kepler's laws and the vis-viva equation, with a live animated orbit — try the ISS, geostationary, or a Molniya orbit.
Stage a rocket, watch it launch, and see if it can actually reach orbit — real vehicle presets included.
Multi-ball collisions and Newton's Cradle, from perfectly elastic to perfectly inelastic — up to 10 balls.