Every formula in the calculator has a story. These plain-language explanations cover what each equation means, where it comes from, and how to use it — each one with a worked example you can reproduce in the calculator.
Why every object with mass pulls on every other, and where the inverse-square law comes from.
Inertia, F = ma, and action-reaction — the foundation of classical mechanics.
The energy of motion, the origin of the one-half factor, and why speed matters more than mass.
What work means in physics and why it always equals the change in kinetic energy.
Mass in motion, and the conservation law that solves collisions without knowing the forces.
The curved flight of anything thrown, and the secret of splitting it into two motions.
Swings, springs and the surprising constancy of the pendulum's rhythm.
How electric charges attract and repel — gravity's far stronger electrical cousin.
The single most useful equation in electricity, with a water-pipe intuition.
Radio waves and gamma rays are the same thing — a tour from longest to shortest waves.
What E = mc² really says about the deep relationship between mass and energy.
A constant that bends space and time and sets the universe's ultimate speed limit.
Why heat and temperature differ, and the laws that govern energy's flow.
Why ships float and ears pop — two simple ratios that govern matter.
Some of physics' greatest leaps began not in a lab but in the imagination. These famous thought experiments reveal deep truths through pure reasoning.
The imagined voyage that proved motion is relative and seeded Einstein's relativity.
The teenage daydream that became special relativity.
How a falling elevator revealed that gravity bends light and space itself.
The imaginary cannon that showed orbiting is just continuous falling.
The cat both alive and dead, and the quantum puzzle it dramatizes.
The being that seemed to break thermodynamics, and the role of information.
The logical argument — no tower needed — that proved all objects fall at the same rate.
A spinning bucket of water and the deep question of whether space itself is absolute.
Behind every great result is a story of insight, accident and persistence. These are the human accounts of how landmark discoveries in physics actually happened.
Two young students, a single afternoon, and a mentor who wouldn't let them lose their nerve.
The echo of the Big Bang began as an annoying hiss two astronomers tried to remove.
Born from a phenomenon light's wave theory couldn't explain — and Einstein's Nobel Prize.
Chasing a misidentified radiation, Chadwick found the missing piece of the atom.
A Belgian priest saw it first — but published in the wrong language and nearly lost the credit.
A quest for the coldest temperatures led to a metal that carries current forever.
Predicted in 1964 and found in 2012 — with the largest machine humanity has ever built.
A cloudy sky, a forgotten plate, and the partnership that revealed matter holds hidden energy.
More guides are added regularly. Have a formula you'd like explained? Let us know.