Here's why:

* Kinetic energy (KE) is the energy an object possesses due to its motion. It's calculated using the formula KE = 1/2 * mv², where:

* m is the mass of the object (measured in kilograms, kg)

* v is the velocity of the object (measured in meters per second, m/s)

* Joule (J) is the standard unit of energy in the International System of Units (SI). It's derived from the units of mass, length, and time (kg, m, and s).

Therefore, the joule (J) is the appropriate SI unit for measuring kinetic energy.