Basic Kinetic Energy Formula

KE = 0.5 * Mass * Velocity²

Where:

KE: Kinetic Energy in Joules (or foot-pounds)
Mass : Mass of the object in kilograms (or slugs)
Velocity: Velocity of the object in m/sec (or ft/sec)

Working Backwards to Find Mass

Mass = KE / (0.5 * Velocity²)

Working Backwards to Find Velocity

Velocity = SQRT (2 * KE / Mass)

Calculating Kinetic Energy in a Closing Situation

KE = 0.5 * Mass (V_Muzzle + V_Target)²

Where:

KE: Kinetic Energy in Joules.
Mass : Mass of the object in kilograms.
V_Muzzle: Velocity of the projectile in m/sec
V_Target: Velocity of the target in m/sec

Typical Kinetic Energies

120mm Sabot (1984): 9.8 MJ
125mm Sabot (1980): 7 MJ
125mm Sabot (1972): 6.1 MJ
125mm Sabot (1962): 5.8 MJ
88mm FlaK: 2.8 MJ:
Ford Explorer at 60 MPH: 0.66 MJ