# Free Online Physics Tools: Formula Calculator, Projectile Motion, Pendulum, Optics, Waves, Circuits

> Free physics tools in your browser: physics formula calculator, projectile motion, pendulum and spring oscillators, collisions and momentum, orbits, lenses and refraction, wave superposition and standing waves, Doppler effect, electric fields, resistor color codes, RC and DC circuits, magnetic fields and induction, charged particles, diffraction and polarization, heat conduction and engine cycles, kinetic theory, fluids, rotation and circular motion, simple machines, the Schrödinger equation, nuclear binding energy, special relativity and blackbody radiation. Interactive simulations that run locally.

- URL: https://qilingtools.com/en/physics
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

## Tools (42)

- [Unit Converter](https://qilingtools.com/en/math/unit): Free online unit converter: length, area, volume, weight, temperature, time, speed, data, pressure, energy and angle — one value converts every unit at once.
- [Vector Calculator](https://qilingtools.com/en/math/vector): Free online vector calculator for 2D and 3D: addition, scalar multiples, dot and cross products, magnitude, angle, unit vector and projections, with checks.
- [Significant Figures Calculator](https://qilingtools.com/en/math/significant-figures): Free online sig fig calculator: count significant figures digit by digit, round to N sig figs or decimals with six rounding modes, and compute by sig fig rules.
- [Tone Generator](https://qilingtools.com/en/audio/tone-generator): Free online tone generator: sine, square, sawtooth and triangle waves from 1 to 20,000 Hz, a note picker, sweeps, white/pink/brown noise and a WAV download.
- [Audio Spectrogram](https://qilingtools.com/en/audio/spectrogram): Free online spectrogram generator: see time, frequency and level from a Hann-windowed STFT, with FFT size, log axis, dB range and colour maps. Exports PNG.
- [Decibel Meter](https://qilingtools.com/en/audio/decibel): Free online decibel meter: measure noise with your mic in real time, A/C/Z weighting, fast/slow response, min/max/average/Leq, 60-second graph and calibration.
- [Physics Formula Calculator](https://qilingtools.com/en/math/physics): Physics formulas solved with steps: SUVAT, projectiles, Newton’s laws, inclines, energy, Ohm’s law, resistors, RC, buoyancy, waves, lenses, gravity.
- [Fourier Series & FFT Visualizer](https://qilingtools.com/en/math/fourier): Fourier series coefficients and animated partial sums for square, sawtooth, triangle or any function (Gibbs), draw-your-own epicycles and FFT spectra.
- [Differential Equation Solver](https://qilingtools.com/en/math/ode): ODE tool: slope fields with click-to-trace solutions (RK4/RK45), Euler vs RK4 errors, phase portraits with equilibrium types, and 2nd-order linear ODEs.
- [Gas Law Calculator](https://qilingtools.com/en/math/gas-law): Free gas law calculator: solve PV=nRT for any variable, combined gas laws, gas density, Dalton's partial pressures, gas over water and van der Waals Z.
- [Half-Life Calculator](https://qilingtools.com/en/math/half-life): Solve radioactive decay for any unknown with 30+ isotopes: decay constant, activity in Bq and Ci, carbon-14 dating and first-order kinetics.
- [Calorimetry & Specific Heat Calculator](https://qilingtools.com/en/math/calorimetry): Free calorimetry calculator: solve q = mcΔT with a specific heat table, find the final temperature of mixtures, get ΔH from coffee-cup and bomb calorimetry.
- [Unit Cells & Crystal Structures](https://qilingtools.com/en/math/crystal): Interactive 3D unit cells (SC, BCC, FCC, HCP, NaCl, CsCl, ZnS, diamond, perovskite) with atoms per cell, coordination number, packing efficiency and density.
- [Light Energy & Atomic Spectra](https://qilingtools.com/en/math/spectroscopy): Convert wavelength, frequency and photon energy (eV, J, kJ/mol), compute hydrogen spectral lines, photoelectric stopping potential and de Broglie wavelength.
- [Projectile Motion Simulator (with Air Resistance)](https://qilingtools.com/en/math/projectile): Animated projectile simulator: set speed, angle, height and gravity (Earth, Moon, Mars, Jupiter), add air drag (RK4), compare paths and find the best angle.
- [Pendulum & Double Pendulum Simulator](https://qilingtools.com/en/math/pendulum): Simulate a nonlinear pendulum (RK4) beside its small-angle twin: exact period, damping, phase space and energy plots, plus a chaotic double pendulum.
- [Collision Simulator (Momentum & Energy)](https://qilingtools.com/en/math/collision): Simulate 1D cart collisions with any masses, velocities and restitution e, see momentum and KE before and after, plus 2D billiard collisions.
- [Orbit & Gravity Simulator](https://qilingtools.com/en/math/orbit): Drag a satellite's velocity to get circular, elliptic or hyperbolic orbits with live orbital elements, Kepler's equal areas, N-body demos and Δv tools.
- [Lens & Mirror Ray Diagram](https://qilingtools.com/en/math/optics): Interactive ray diagrams for converging and diverging lenses and concave and convex mirrors: drag the object to see image position, size and magnification.
- [Refraction & Total Internal Reflection Simulator](https://qilingtools.com/en/math/refraction): Drag a light ray through water, glass or diamond: refraction angle, Fresnel reflectance, critical angle, Brewster angle, prism dispersion and apparent depth.
- [Wave Superposition & Standing Waves](https://qilingtools.com/en/math/waves): Interactive wave simulator: superpose traveling waves, see standing waves on strings and pipes with nodes and harmonics, hear beats, and explore a ripple tank.
- [Doppler Effect Simulator](https://qilingtools.com/en/math/doppler): Doppler effect calculator with animation: moving source and observer, Mach cone and sonic boom, relativistic redshift, radar speed guns and pass-by audio.
- [Electric Field & Potential Simulator](https://qilingtools.com/en/math/electric-field): Drag point charges and watch electric field lines and equipotentials update live. Probe E and V anywhere, compute Coulomb forces and launch a test charge.
- [Resistor Color Code Calculator](https://qilingtools.com/en/math/resistor-color): Resistor color code calculator for 4, 5 and 6 bands: value, tolerance and tempco; find bands for any value snapped to E12/E24/E96; decode SMD codes like 472.
- [RC / RL / RLC Circuit Simulator](https://qilingtools.com/en/math/rc-circuit): Simulate RC charging and discharging, RL current and RLC step response with τ marks, plus resonance, Q, bandwidth, filter cutoff, Bode plots and live phasors.
- [Special Relativity Calculator & Spacetime Diagram](https://qilingtools.com/en/math/relativity): Lorentz factor, time dilation and length contraction with a rocket animation, relativistic energy, velocity addition, twin paradox and a Minkowski diagram.
- [Blackbody Radiation & Planck's Law Visualizer](https://qilingtools.com/en/math/blackbody): Plot Planck blackbody curves for several temperatures with Wien peaks, σT⁴ power, visible fraction, blackbody colour and the Rayleigh–Jeans comparison.
- [Spring Oscillator & Resonance](https://qilingtools.com/en/math/spring): Animated spring-mass-damper with driving force: live x(t), damping regime with ω₀, ζ and Q, resonance curves, and coupled normal modes with beats.
- [Magnetic Field Simulator](https://qilingtools.com/en/math/magnetic-field): Drag current-carrying wires and bar magnets to see field lines, compass needles and |B|. Exact loop and solenoid fields, on-axis B(z) and forces between wires.
- [Charged Particle in E & B Fields](https://qilingtools.com/en/math/charged-particle): Electrons, protons or alphas in any uniform E and B in 3D: gyroradius, period, pitch and E×B drift, plus a velocity selector, mass spectrometer and cyclotron.
- [Electromagnetic Induction & Generator](https://qilingtools.com/en/math/induction): Move a magnet through a coil and watch flux, EMF and the galvanometer obey Lenz's law, plus an AC generator, a rod on rails and a transformer.
- [DC Circuit Builder & Solver](https://qilingtools.com/en/math/dc-circuit): Build DC circuits on a grid with batteries, resistors, bulbs, switches and meters. Nodal analysis gives every voltage, current and power, plus KCL/KVL.
- [Diffraction, Interference & Polarization](https://qilingtools.com/en/math/diffraction): Free wave-optics simulator: slit and grating patterns in white light, Airy disks and the Rayleigh limit, thin-film colours, Newton's rings and Malus's law.
- [Heat Conduction Simulator](https://qilingtools.com/en/math/heat-conduction): Simulate heat conduction: animated 1D rod (Crank–Nicolson) with real materials, paintable 2D plate, composite wall U-value calculator and Newton cooling fit.
- [Fluid Mechanics Simulator (Bernoulli, Buoyancy, Pipe Flow)](https://qilingtools.com/en/math/fluid): Interactive fluid mechanics: drag a pipe to see Bernoulli at work, Venturi meter, Torricelli tank draining, buoyancy, Pascal press and Reynolds number.
- [Moment of Inertia & Rotational Dynamics](https://qilingtools.com/en/math/rotation): Moment of inertia for rods, disks, spheres, plates and composites with the parallel-axis theorem; rolling race, spinning skater, Atwood machine.
- [Circular Motion & Centripetal Force Simulator](https://qilingtools.com/en/math/circular-motion): Animated circular motion: velocity and centripetal vectors, cut the string, centrifugal force, banked curves, coaster loops, conical pendulum.
- [Quantum Mechanics Simulator (Schrödinger Equation)](https://qilingtools.com/en/math/quantum): Solve the 1D Schrödinger equation online: energy levels and wavefunctions for wells, oscillators or a drawn potential, plus tunneling wave packets and T(E).
- [Heat Engine Cycles & PV Diagrams](https://qilingtools.com/en/math/thermo-cycle): Interactive PV and TS diagrams for Carnot, Otto, Diesel, Brayton, Stirling and custom cycles. Drag states, see Q, W, ΔU, ΔS per step, efficiency and COP.
- [Kinetic Theory of Gases Simulator](https://qilingtools.com/en/math/gas-kinetics): Watch hundreds of colliding molecules: speed histogram vs Maxwell–Boltzmann, pressure from wall impacts, mean free path, piston heating, effusion and mixing.
- [Nuclear Binding Energy, Fission & Fusion](https://qilingtools.com/en/math/nuclear): Binding energy per nucleon from AME2020 masses, mass defect and SEMF terms for any nuclide, and Q-values for fusion, fission and decay vs TNT and coal.
- [Simple Machines Simulator (Levers, Pulleys, Gears)](https://qilingtools.com/en/math/simple-machines): Drag a lever’s fulcrum, lift loads with pulleys, mesh gear trains and bike gears, and compare inclines, screw jacks and wedges: force and efficiency.