# Kinetic Energy Calculator (KE = ½mv²) Compute kinetic energy, mass, or velocity from the other two, with momentum and km/h conversion > Canonical page: https://elysiatools.com/en/tools/kinetic-energy-calculator - **Category:** Math & Numbers - **Keywords:** kinetic energy, energy, mass, velocity, speed, joule, momentum, physics, mechanics, ke=1/2mv² ## Overview Kinetic energy is the energy of motion. Equations (three-way solver): - Kinetic energy: KE = ½ · m · v² (J) - Mass: m = 2 · KE / v² - Velocity: v = √(2 · KE / m) Momentum: p = m · v. Velocity in km/h = v · 3.6. ## Inputs - **Solve For** (select) - **Kinetic Energy (KE, J)** (number): leave blank when solving for kinetic energy - **Mass (m, kg)** (number): leave blank when solving for mass - **Velocity (v, m/s)** (number): leave blank when solving for velocity ## When to use - When solving physics homework problems involving moving objects and energy conservation. - When analyzing vehicle crash dynamics or impact forces by calculating the kinetic energy of a moving mass. - When converting linear velocity from meters per second to kilometers per hour while determining momentum. ## How it works - Select the variable you want to calculate (Kinetic Energy, Mass, or Velocity) from the dropdown menu. - Input the two known values in their respective fields (Joules for energy, kilograms for mass, or meters per second for velocity). - Click calculate to compute the missing variable, momentum, and alternative velocity units. ## Use cases - Calculating the kinetic energy of a projectile to evaluate impact force. - Determining the required mass of a moving component given a target velocity and energy limit. - Finding the velocity of a falling object just before impact based on its potential energy converted to kinetic energy. ## Frequently asked questions ### What units are used for the inputs? Mass is measured in kilograms (kg), velocity in meters per second (m/s), and kinetic energy in Joules (J). ### How does the calculator compute momentum? Momentum is calculated using the formula p = m · v, where m is mass and v is velocity. ### Can I calculate velocity in km/h? Yes, the calculator automatically converts the velocity in meters per second to kilometers per hour (km/h) by multiplying it by 3.6. ### What happens if I leave the target variable field blank? The calculator will ignore any value in the field selected under 'Solve For' and compute it based on the other two inputs. ### Does this calculator account for relativistic speeds? No, it uses classical Newtonian mechanics (KE = ½mv²), which is accurate for speeds much slower than the speed of light. ## Related tools - [Dimensional Analysis Unit Cancellation Tutor](https://elysiatools.com/en/tools/dimensional-analysis-unit-cancellation-tutor): Step-by-step factor-label unit cancellation with inverted-factor diagnosis and optional student-answer checking. - [Force Calculator (F = m·a)](https://elysiatools.com/en/tools/force-calculator): Compute force, mass, or acceleration from Newton's second law, with weight on Earth - [Momentum Calculator (p = mv)](https://elysiatools.com/en/tools/momentum-calculator): Compute linear momentum, mass, or velocity from the other two, with kinetic energy and km/h conversion - [Ohm's Law and Power Triangle Calculator](https://elysiatools.com/en/tools/ohms-law-calculator): Solve for two unknowns among Voltage, Current, Resistance and Power from any two given values, with visual triangles and AC power-factor support - [Pressure Calculator & Converter (P=F/A, Pa/kPa/bar/atm/psi)](https://elysiatools.com/en/tools/pressure-conversion): Solve pressure, force, or area from P=F/A, and convert between Pa, kPa, MPa, bar, atm, psi, Torr, inHg, kgf/cm² - [Reaction Rate Calculator](https://elysiatools.com/en/tools/reaction-rate-calculator): Fit zero-order, first-order, and second-order rate equations to concentration-time data. 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