An example is the calculation of the rotational kinetic energy of the Earth. As the Earth has a sidereal rotation period of 23.93 hours, it has an angular velocity of 7.29×10−5 rad·s−1.[2] The Earth has a moment of inertia, I = 8.04×1037 kg·m2.[3] Therefore, it has a rotational kinetic energy of 2.14×1029 J.