A rolling body carries both translational and rotational kinetic energy, so its total is KE = 0.5 * m * v^2 + 0.5 * I * omega^2, linked by the rolling condition v = omega * R. The arithmetic is exact only for the stated mass, speed, inertia, and angular speed in the ideal rigid-body, no-slip model. Real systems add distributed-mass geometry, slipping, friction, bearing losses, axis alignment, sensor calibration, finite precision, and measurement uncertainty.
A rolling object carries two checked kinetic-energy ledgers. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Rolling energy has translation plus rotation
The translational part is 9 joules and the rotational part is 9 joules.