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Kinetic Energy Calculator

Solve KE = ½ m v² for energy, or work backwards to the mass or velocity.

Reviewed by the OmniCalc teamMethod verified 2026-07-01

Solve for

Result

9J

Kinetic energy 9 J
Show steps
  1. KE = ½ × m × v² = ½ × 2 kg × (3 m/s)² = 9 J.

How to use the kinetic energy calculator

  1. 1Choose to solve for energy, mass or velocity.
  2. 2Enter the two known values in kg, m/s or J.
  3. 3Read the result; Show steps spells out the substitution.

Why speed is dangerous

Because of the v²term, going from 50 to 100 km/h doesn’t double the kinetic energy — it quadruples it. The same mass now carries four times the energy to shed in a stop or a crash.

Frequently asked questions

What is the kinetic energy formula?

Kinetic energy is one-half mass times velocity squared: KE = ½ × m × v². It measures the energy an object carries because of its motion.

Why does speed matter more than mass?

Because velocity is squared. Doubling the mass doubles the energy, but doubling the speed quadruples it — which is why crash energy climbs so steeply with speed.

What units come out?

Joules (J) when mass is in kilograms and velocity in metres per second, since 1 J = 1 kg·m²/s².