# Physics Calculator - Kinematics, Forces, Circuits, Optics

> Physics formulas solved with steps: SUVAT, projectiles, Newton’s laws, inclines, energy, Ohm’s law, resistors, RC, buoyancy, waves, lenses, gravity.

- URL: https://qilingtools.com/en/math/physics
- Category: Physics Tools (https://qilingtools.com/en/physics)
- Tags: [Physics](https://qilingtools.com/en/tags/physics)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

This physics solver is organised by topic: fill in what you know, leave the unknowns blank, and it picks the right formula, rearranges it, substitutes the numbers and shows every step. In kinematics, any three of the five SUVAT quantities (displacement, initial velocity, final velocity, acceleration, time) give the other two, with both roots listed when a quadratic appears; for projectiles, enter launch speed, angle and height to get the maximum height, time of flight, range and impact velocity, with the trajectory drawn. Forces cover Newton’s second law, weight, friction, Hooke’s law, circular motion and an inclined plane with a force diagram that tells you whether the block slides, its acceleration and the critical angle. Work and energy include work, kinetic, gravitational and elastic potential energy, power, momentum and impulse, and efficiency. In circuits, Ohm’s law and electrical power solve U, I, R and P from any two, any number of resistors combine in series and parallel, and an RC section handles the time constant and charging. There’s also pressure, hydrostatic pressure, buoyancy and floating fraction, wave speed v = fλ, the thin lens and mirror equation with a ray diagram, and universal gravitation with orbital speed, period and escape velocity. Every quantity has a unit menu (km/h, mph, kWh, atm, μF, Earth masses…), and results can be shown in any unit.

## How to use

1. Choose a topic and formula, such as Kinematics → SUVAT equations
2. Enter the known values with their units and leave the unknowns blank
3. Read the results and the substituted working, and switch the result units if you like

## Features

- Any combination of knowns: the right formula is chosen and rearranged automatically
- Every step shows the formula, its rearranged form and the substituted numbers
- SUVAT: any three of five, with both roots of a quadratic
- Projectile trajectory plot with maximum height, flight time, range and impact speed
- Inclined plane force diagram: components, normal force, friction, sliding and acceleration
- Ohm’s law and power, series/parallel resistors, RC charging
- Thin lens and mirror images (real/virtual, magnification) with a ray diagram
- Pressure, buoyancy, waves, gravitation and orbits; free unit conversion

## FAQ

### Which SUVAT equation should I use?

Each equation leaves out one of s, u, v, a and t: v = u + at has no s, s = ut + ½at² has no v, s = (u + v)t/2 has no a, and v² = u² + 2as has no t. Pick the one without the quantity you’re neither given nor asked for. The solver makes the same choice automatically and shows the rearrangement.

### Why do I sometimes get two solutions?

A quadratic can have two valid roots. A ball thrown upwards passes the same height twice — once on the way up and once on the way down — so finding time from displacement gives two times, and taking a square root for velocity gives two directions. Both solutions are listed so you can choose the one that fits the question.

### What sign convention does the lens calculator use?

It uses “real is positive”: the object distance u is positive, the image distance v is positive for a real image and negative for a virtual one, and converging lenses and concave mirrors have positive focal lengths while diverging lenses and convex mirrors have negative ones. The equation is 1/f = 1/u + 1/v with magnification m = −v/u; negative m means inverted and |m| > 1 means enlarged. Courses using the Cartesian convention write it differently but reach the same conclusions about the image.

### Can I mix units?

Yes. Each input has its own unit menu, and values are converted to SI units (m, kg, s, N, J, W, Pa…) before calculating. The working shows the SI values, and the results are displayed in whatever unit you choose — enter 72 km/h and the substitution uses 20 m/s.

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