Live tools 220

Physics you can compute: motion, energy, matter & waves.

Free-fall timing, F = ma, SUVAT kinematics, kinetic energy, wattage, heat flow, density, and wave speed — the equations of the physical world, solved as you type.

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Hand-picked starters.

Mechanics · 6 tools

Motion, force, and the equations behind them.

Free-fall timing, Newton's second law, SUVAT kinematics, and velocity — solve for any variable in the equations of motion, instantly.

Flagship · Drop solver

Free Fall Calculator

Drag the drop height — fall time and impact speed update live from t = √(2h/g).

Height 10 m

1.43 s31 mph impact · 14.0 m/s Open full calculator

Newton's second law

Force Calculator

Solve F = ma for force, mass, or acceleration — newtons, pounds-force, and g-units converted automatically.

F = m · asolve any variable

More mechanics tools 4 more

Velocityv = d / t KinematicsSUVAT + projectiles Newton's Lawsfriction & inclines Projectile Motionrange & trajectory

Energy · 3 tools

Joules, watts, and where the energy goes.

Kinetic and potential energy, mechanical and electrical power, and the heat equation — with the unit conversions handled for you.

9.81m/s²

Standard gravity — the g inside every potential-energy and free-fall result.

Flagship · Energy of motion

Energy & Work Calculator

Drag mass and speed — kinetic energy updates live from KE = ½mv², with the v² scaling shown on the bars.

Mass 1,500 kg

Speed 14 m/s

147 kJ41 Wh equiv · 31 mph Open full calculator

Work over time

Power Calculator

Mechanical or electrical power in watts — from work and time, force and velocity, or volts and amps.

P = W / twatts, hp & kW

Heat & applied energy 3 tools

Heat TransferQ = mcΔT Heat Lossconstruction & DIY Solar Panel Savingsenvironment

Matter & Waves · 2 tools

What things are made of, and how they move through it.

Density and sink-or-float math on one side, the wave equation on the other — matter and the signals that travel through it.

Flagship · Sink or float

Density Calculator

Drag mass and volume — density lands on the material trail and the widget tells you whether it floats in water.

Mass 2 kg

Volume 3 L

667 kg/m³SG 0.67 · floats Open full calculator

The wave equation

Wave & Frequency Calculator

Frequency, wavelength, period, or speed — solve v = f × λ for sound, light, and water waves.

v = f × λany wave, any variable

Cross-references 2 more

Volumemath & science Scientific Notationmath & science

Key terms & formulas

The physics vocabulary, decoded.

Every definition links to the calculator that puts the term to work. Browse the full glossary →

Standard gravity (g)The standard acceleration due to gravity at Earth's surface: 9.80665 m/s² (about 32.174 ft/s²). Every falling object in a vacuum gains this much speed each second, regardless of its mass. Newton (N)The SI unit of force. One newton accelerates a 1 kg mass at 1 m/s² — roughly the weight of a small apple at Earth's surface. F = ma ties force, mass, and acceleration together. Joule (J)The SI unit of energy and work. One joule is the work done by a 1 N force acting over 1 m. Kinetic energy is KE = ½mv², so doubling speed quadruples the energy. Watt (W)The SI unit of power — one joule per second. Power measures how fast energy is transferred or converted: 746 W equals 1 horsepower, and a kilowatt-hour is 3.6 million joules. Specific gravityThe ratio of a material's density to the density of water (1,000 kg/m³). Below 1 the material floats; above 1 it sinks. A floating object sits with roughly its specific gravity as the submerged fraction of its volume. Hertz (Hz)The SI unit of frequency — one cycle per second. For any wave, speed equals frequency times wavelength (v = f × λ), so higher frequency means shorter wavelength at the same speed.

t = √(2h / g) · v = g · tFree-fall time and impact speed from drop height — vacuum kinematics with g = 9.80665 m/s².

KE = ½ · m · v²Kinetic energy grows with the square of speed — double the speed, quadruple the energy.

ρ = m / V · v = f × λDensity (below 1,000 kg/m³ floats in water) and the wave equation tying speed, frequency, and wavelength.

Frequently asked questions

What value of gravity do the calculators use?

Standard gravity: g = 9.80665 m/s² (32.174 ft/s²), the internationally agreed reference value. Real local gravity varies by about ±0.3% with latitude and altitude — negligible for everyday problems, which is why textbooks and these tools use the standard constant.

Do the free-fall results include air resistance?

No — the quick solver and the calculator's default mode use ideal (vacuum) kinematics: t = √(2h/g). For compact, dense objects over short drops the error is small, but light or draggy objects approach a terminal velocity and fall slower than the ideal prediction. The full Free Fall Calculator explains when the vacuum model stops being a good approximation.

Can I solve for any variable, not just the usual one?

Yes. The mechanics tools are solve-for calculators: enter any two of force, mass, and acceleration and the Force Calculator returns the third; the Kinematics Calculator solves SUVAT for velocity, acceleration, distance, or time; the Wave Calculator rearranges v = f × λ for whichever variable you leave blank.

Why does kinetic energy quadruple when speed only doubles?

Because KE = ½mv² depends on the square of speed. At 2× the speed, v² is 4× as large, so the energy — and roughly the braking distance needed to shed it — is 4× as large. The Energy & Work widget's bar chart shows this scaling live as you drag the speed slider.

What units do the science calculators work in?

SI units are the default — meters, kilograms, seconds, newtons, joules, watts — because the physics formulas are cleanest there. Every calculator also converts to and from common US units (feet, pounds, mph, horsepower, BTU) so you can enter what you have and read out what you need.