# SolvedPhysics

> Free step-by-step physics equation solvers and guides for UK GCSE (AQA, Edexcel, OCR) and A-level students. Each solver chooses the right equation, rearranges it, converts units to SI, and shows every line of working the way examiners expect. Written and checked by Mehmood Kakar, a physics teacher and engineer with 8 years of teaching experience.

## Solvers

- [Kinetic energy calculator](https://solvedphysics.com/gcse/energy/kinetic-energy-calculator/): Find kinetic energy, mass or speed with Ek = ½mv². Converts g, tonnes, km/h, cm/s, kJ and MJ.
- [Gravitational potential energy calculator](https://solvedphysics.com/gcse/energy/gravitational-potential-energy-calculator/): Find GPE, mass, height or g with Ep = mgh. g defaults to 9.8 N/kg; converts g, cm, km and kJ.
- [Elastic potential energy calculator](https://solvedphysics.com/gcse/energy/elastic-potential-energy-calculator/): Find elastic potential energy, spring constant or extension with Ee = ½ke². Converts cm, mm and N/cm.
- [Specific heat capacity calculator](https://solvedphysics.com/gcse/energy/specific-heat-capacity-calculator/): Find energy, mass, specific heat capacity or temperature change with ΔE = mcΔθ. Water is 4200 J/kg °C.
- [Power calculator](https://solvedphysics.com/gcse/energy/power-calculator/): Find power, energy transferred (or work done) or time with P = E/t. Converts kW, kJ, minutes and hours.
- [Efficiency calculator](https://solvedphysics.com/gcse/energy/efficiency-calculator/): Find efficiency, useful output or total input for energy or power; answers as a decimal and a percentage.
- [Charge flow calculator](https://solvedphysics.com/gcse/electricity/charge-calculator/): Find charge, current or time with Q = It. Converts mA, minutes and hours.
- [Ohm's law calculator](https://solvedphysics.com/gcse/electricity/ohms-law-calculator/): Find potential difference, current or resistance with V = IR. Converts mA, kΩ, MΩ, mV and kV.
- [Electrical power calculator](https://solvedphysics.com/gcse/electricity/electrical-power-calculator/): Find power, potential difference or current with P = VI. UK mains is 230 V.
- [Power and resistance calculator](https://solvedphysics.com/gcse/electricity/power-resistance-calculator/): Find power, current or resistance with P = I²R, including the square-root step for current.
- [Energy transferred calculator](https://solvedphysics.com/gcse/electricity/energy-transferred-calculator/): Find energy, charge or potential difference with E = QV (1 V = 1 J/C).
- [Speed, distance and time calculator](https://solvedphysics.com/gcse/forces/speed-calculator/): Find speed, distance or time with s = vt. Converts km, minutes, hours and km/h.

## Topic hubs

- [GCSE Energy solvers](https://solvedphysics.com/gcse/energy/)
- [GCSE Electricity solvers](https://solvedphysics.com/gcse/electricity/)
- [GCSE Forces solvers](https://solvedphysics.com/gcse/forces/)

## Guides

- [How to rearrange physics equations](https://solvedphysics.com/guides/how-to-rearrange-physics-equations/): The balance method, formula triangles and worked examples for V = IR, Ep = mgh, Ek = ½mv², P = I²R and v² − u² = 2as.
- [GCSE physics units and prefixes](https://solvedphysics.com/guides/gcse-physics-units-and-prefixes/): SI units for every GCSE quantity, prefixes from nano to giga, and common conversions including km/h to m/s (÷ 3.6), cm² to m² (÷ 10,000) and cm³ to m³ (÷ 1,000,000).

- [How to show your working in GCSE physics calculations](https://solvedphysics.com/guides/how-to-show-working-in-physics-calculations/): A four-line layout (equation, convert, substitute, answer with unit), rounding rules and multi-step questions.
- [7 rearranging mistakes that cost GCSE physics marks](https://solvedphysics.com/guides/rearranging-mistakes-gcse-physics/): Flipped divisions, dividing by one term, losing the 2 from ½, missing square roots, sign errors and calculator order.

- [Kinetic energy exam questions with worked answers](https://solvedphysics.com/guides/kinetic-energy-exam-questions/): Seven GCSE-style questions: finding Ek, speed and mass, grams and km/h conversions, doubling speed (×4), and a falling ball (GPE lost = Ek gained).
- [Gravitational potential energy exam questions with worked answers](https://solvedphysics.com/guides/gravitational-potential-energy-exam-questions/): Six GCSE-style questions: finding Ep, height and mass, unit conversions, g on the Moon (1.6 N/kg), and GPE with power.

## About

- [About SolvedPhysics and the author](https://solvedphysics.com/about/): Who writes and checks the content, and how it is checked against the AQA GCSE Physics (8463) specification.

## Key facts

- For AQA GCSE Physics (8463), all physics equations are printed on the exam equation sheet; marks are mainly lost on choosing, rearranging, unit conversion and showing working.
- SI units used throughout: energy in joules (J), mass in kilograms (kg), distance in metres (m), time in seconds (s), speed in metres per second (m/s), gravitational field strength in N/kg, charge in coulombs (C), current in amperes (A), potential difference in volts (V), resistance in ohms (Ω), power in watts (W).
- UK mains electricity is about 230 V at 50 Hz.