What is kinetic energy?

Kinetic energy (KE) is the energy an object possesses due to its motion. It equals one-half times the object's mass times the square of its velocity: KE = ½mv². The SI unit is the joule (J). Kinetic energy is always positive and increases with the square of speed.

Why does kinetic energy depend on velocity squared?

Kinetic energy is derived from the work-energy theorem. Doubling an object's speed quadruples its kinetic energy because the velocity term is squared in KE = ½mv². This non-linear relationship is why high-speed impacts are so destructive compared to low-speed ones.

What units does this calculator support?

Mass: kilograms (kg), grams (g), pounds (lb), and slugs. Velocity: meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), and feet per second (ft/s). Energy output is shown in joules (J), kilojoules (kJ), foot-pounds (ft·lbf), and BTU.

How do I solve for mass or velocity?

Switch the "Solve for" selector to Mass or Velocity. Enter the known kinetic energy and the other variable. The calculator rearranges the formula: m = 2·KE ÷ v² for mass, and v = √(2·KE ÷ m) for velocity.

What is the difference between kinetic energy and momentum?

Momentum (p = mv) is a vector quantity proportional to velocity, while kinetic energy (KE = ½mv²) is a scalar proportional to velocity squared. Two objects can have the same momentum but very different kinetic energies if their masses differ. Both are conserved under different conditions in collision problems.

Kinetic Energy Calculator

Name: Kinetic Energy Calculator
Availability: InStock
Author: Nham Vu

Calculate kinetic energy (KE = ½mv²) or solve for mass or velocity, with full metric and imperial unit support.

Kinetic Energy Calculator

Solve for

Mass

Velocity

KE = ½ × m × v²

Enter two known values on the left to compute the result.

KE = ½mv²

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Summary

Calculate kinetic energy (KE = ½mv²) or solve for mass or velocity, with full metric and imperial unit support.

How it works

Select what you want to solve for: Kinetic Energy, Mass, or Velocity.
Enter the two known values and select their units from the dropdowns.
The result appears instantly along with all unit conversions.
Click any conversion card to copy that value to your clipboard.
Use the Clear button to reset inputs and start a new calculation.

Use cases

Solve physics homework problems involving kinetic energy and motion.
Calculate the energy of a moving vehicle at a given speed.
Determine how fast an object must travel to reach a target kinetic energy.
Find the mass of an object from its speed and kinetic energy.
Convert kinetic energy between joules, kilojoules, foot-pounds, and BTUs.
Analyze collisions and energy transfer in mechanics coursework.
Estimate the stopping energy required for a braking system.
Compare the kinetic energy of objects at different speeds or masses.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu