Physics Calculators
Motion, energy, electricity and gases
Mechanics: motion, force and energy
The mechanics tools follow one chain. Force is mass times acceleration; acceleration is a change in velocity over time; velocity over time is distance. Given any two links you can recover the rest, and the acceleration calculator solves the full set of motion equations rather than only the one you asked about, because the others are usually what you needed next.
Energy splits into two forms that convert into each other. Kinetic energy is ½mv², which is why doubling a vehicle’s speed quadruples the energy a crash has to dissipate — the single most useful physical fact on this page. Gravitational potential energy is mgh, and the potential energy calculator also gives the impact speed if the object falls, which is the same energy arriving in a different form. Momentum, mv, is the third member of the family and behaves differently: it is linear in speed, and it is what determines the impulse needed to stop something.
Electricity, gases and decay
Ohm’s law relates voltage, current and resistance, and the calculator solves for any of them from the other two while also giving power — the quantity that actually determines heat, cable sizing and what a supply must deliver.
The ideal gas law, PV = nRT, ties pressure, volume, quantity and temperature into one relationship: leave any one blank and the calculator returns it. It holds well for real gases at ordinary pressures and temperatures and drifts as you approach condensation, which is worth knowing before trusting it near a phase change.
Half-life describes anything decaying at a rate proportional to what remains — radioactive isotopes, drug concentrations, capacitor discharge. The calculator works in both directions: how much is left after a given time, or the half-life implied by a measured drop. Density and pressure round out the set, each with the unit conversions the quantity is normally quoted in.
Physics calculators — common questions
What units do these calculators use?
SI throughout for the calculation — kilograms, metres, seconds, newtons, joules, pascals — with input and output offered in the common alternatives as well, so you can enter kilometres per hour and read pressure in psi without converting by hand. Each page states its units next to every field.
Why does doubling speed more than double stopping distance?
Because kinetic energy goes as the square of velocity. Twice the speed is four times the energy, and the brakes have to dissipate all of it, so the braking distance alone quadruples — before adding the reaction distance, which merely doubles. The kinetic energy calculator shows the squared term explicitly for this reason.
Is the ideal gas law accurate for real gases?
Close enough for most work at everyday pressures and temperatures well above the boiling point. It assumes molecules have no volume and do not attract each other, so it drifts under high pressure or near condensation, where a real-gas equation of state is needed instead.
What is the difference between energy and power?
Energy is a quantity; power is a rate — energy per unit time. A joule is energy, a watt is one joule per second. They cannot be converted without knowing the duration involved, which is exactly what the joules to watts converter asks for, and mixing them up is why an appliance’s wattage tells you nothing about its running cost until you say how long it runs.