The rotational energy or angular kinetic energy is the kinetic energy due to the rotation of an object and is part of its total kinetic energy. Looking at rotational energy separately in an object's centre of mass frame, one gets the following dependence on the object's moment of inertia: Kinetic energy (SI unit: the Joule) is energy that a body possesses as a result of its motion. ... The center of mass or center of inertia of an object is a point at which the objects mass can be assumed, for many purposes, to be concentrated. ... Frame of reference - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Moment of inertia (SI unit kilogram metre squared kg m2) quantifies the rotational inertia of an object, i. ...

In SI units, rotational energy is measured in joules. Cover of brochure The International System of Units. ... The joule (symbol: J) is the SI unit of energy, or work with base units of kg·m2/s2. ...

The energy required for / released during rotation is the torque times the rotation angle. The instantaneous power of an angularly accelerating body is the torque times the angular frequency. In physics, power (symbol: P) is the amount of work done per unit of time. ...

Note the close relationship between the results for linear (or translational) and rotational motion; the formula for the

In the rotating system, the moment of inertia, I, takes the role of the mass, m, and the angular velocity, ω, takes the role of the linear velocity, v. Moment of inertia (SI unit kilogram metre squared kg m2) quantifies the rotational inertia of an object, i. ... Angular velocity describes the speed of rotation. ...

The rotational energy of a rolling cylinder varies from one half of the translational energy (if it is massive) to the same as the translational energy (if it is hollow). A driving wheel on a steam locomotive. ... A right circular cylinder In mathematics, a cylinder is a quadric, i. ...

As an example, let us calculate the rotational kinetic energy of the Earth. As the Earth has a period of about 23.93 hours, it has an angular velocity of 7.29×10^-5 rad·s^-1. Assuming that the Earth is perfectly spherical and uniform in mass density, it has a moment of inertia, I = 9.72×10³⁷ kg·m². Therefore, it has a rotational kinetic energy of 2.58×10²⁹ J.

Part of it can be tapped using tidal power. This creates additional friction of the two global tidal waves, infinitesimally slowing down Earth's angular velocity ω. Due to conservation of angular momentum this process transfers angular momentum to the Moon's orbital motion, increasing its distance from Earth and its orbital period (see tidal locking for a more detailed explanation of this process). Tidal power is a means of electricity generation achieved by capturing the energy contained in moving water mass due to tides. ... In physics the angular momentum of an object with respect to a reference point is a measure for the extent to which, and the direction in which, the object rotates about the reference point. ... In physics the angular momentum of an object with respect to a reference point is a measure for the extent to which, and the direction in which, the object rotates about the reference point. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... Tidal locking makes one side of an astronomical body always face another, like the Moon facing the Earth. ...

See also

• Flywheel
• Rigid rotor
• Rotational spectroscopy