How to use the physics formula solver
- Choose a formula: speed, acceleration, force, energy, power, density, pressure, Ohm's law, waves, specific heat capacity and more.
- Type the values you know in SI units, and leave the quantity you want to find empty.
- The answer appears with its unit and the substitution used, so you can check your own working.
Rearranging physics equations
Most school physics problems use a small set of equations, and the skill lies in choosing the right one and rearranging it. In a three-quantity equation like v = d ÷ t, the "formula triangle" trick works: cover the quantity you want and the others show how to calculate it (d = v × t, t = d ÷ v). Equations with squares, such as kinetic energy (½mv²) or v² = u² + 2as, need square roots when solving for speed, which this solver handles for you.
Always convert to SI units first: kilograms not grams, metres not centimetres, seconds not minutes, joules and watts. That is the most common source of wrong answers. Use the solver to check homework and revision questions rather than to replace the working; examiners give marks for writing the equation, substituting the values and stating the unit. Equations are those used in GCSE, IGCSE and high-school physics. Everything is calculated in your browser.
What is g in physics?
Gravitational field strength, 9.81 N/kg on Earth (often rounded to 9.8 or 10 in exams).
How do I find speed from kinetic energy?
v = √(2Eₖ ÷ m). Choose the kinetic energy formula, enter energy and mass, and leave speed empty.
Why is my answer wrong by a factor of 1,000?
Usually a unit conversion: grams instead of kilograms, kilometres instead of metres, or kilowatts instead of watts.