⚡ Kinetic Energy Calculator
Enter mass and velocity to calculate kinetic energy E = ½mv², with relativistic correction comparison
About Kinetic Energy Calculator
What is the kinetic energy formula?
The classical kinetic energy formula is E = ½mv², where E is kinetic energy (Joules), m is mass (kilograms), and v is velocity (meters/second). When an object's speed approaches the speed of light, the relativistic kinetic energy formula E = (γ-1)mc² must be used, where γ = 1/√(1-v²/c²) is the Lorentz factor.
When should I use the relativistic kinetic energy formula?
When an object's speed exceeds 10% of the speed of light (0.1c ≈ 3×10⁷ m/s), the classical kinetic energy formula's error becomes significant, and the relativistic formula should be used. At 0.1c the classical formula underestimates by about 0.5%, at 0.5c by about 19%, and at 0.9c the error exceeds 100%. Everyday speeds are far below 0.1c, so the classical formula is fully applicable.