Kinetic energy (KE) is the energy of motion. Any moving object — from a baseball to a planet — has kinetic energy proportional to its mass and the square of its velocity.
Formula
KE = ½mv², where m = mass (kg), v = velocity (m/s). Units: Joules (J).
Key Properties
- Doubling velocity quadruples kinetic energy (v² relationship)
- A car at 60 mph has 4× the KE of one at 30 mph — this is why high-speed crashes are so much more dangerous
Work-Energy Theorem
The net work done on an object equals its change in kinetic energy: W = ΔKE.