Wiktionary
n. (context physics English) The vector product that describes the rotary inertia of a system about an axis and is conserved in a closed system. For an isolated rigid body, it is a measure of the extent to which an object will continue to rotate in the absence of an applied torque.
WordNet
n. the product of the momentum of a rotating body and its distance from the axis of rotation; "any rotating body has an angular momentum about its center of mass"; "angular momentum makes the world go round"
Wikipedia
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important quantity in physics because it is a conserved quantity – the angular momentum of a system remains constant unless acted on by an external torque.
The definition of angular momentum for a point particle is a pseudovector r×p, the cross product of the particle's position vector r (relative to some origin) and its momentum vector p = mv. This definition can be applied to each point in continua like solids or fluids, or physical fields. Unlike momentum, angular momentum does depend on where the origin is chosen, since the particle's position is measured from it. The angular momentum of an object can also be connected to the angular velocity ω of the object (how fast it rotates about an axis) via the moment of inertia I (which depends on the shape and distribution of mass about the axis of rotation). However, while ω always points in the direction of the rotation axis, the angular momentum L may point in a different direction depending on how the mass is distributed.
Angular momentum is additive; the total angular momentum of a system is the (pseudo) vector sum of the angular momenta. For continua or fields one uses integration. The total angular momentum of anything can always be split into the sum of two main components: "orbital" angular momentum about an axis outside the object, plus "spin" angular momentum through the centre of mass of the object.
Torque can be defined as the rate of change of angular momentum, analogous to force. The conservation of angular momentum helps explain many observed phenomena, for example the increase in rotational speed of a spinning figure skater as the skater's arms are contracted, the high rotational rates of neutron stars, the falling cat problem, and precession of tops and gyros. Applications include the gyrocompass, control moment gyroscope, inertial guidance systems, reaction wheels, flying discs or Frisbees and Earth's rotation to name a few. In general, conservation does limit the possible motion of a system, but does not uniquely determine what the exact motion is.
In quantum mechanics, angular momentum is an operator with quantized eigenvalues. Angular momentum is subject to the Heisenberg uncertainty principle, meaning only one component can be measured with definite precision, the other two cannot. Also, the " spin" of elementary particles does not correspond to literal spinning motion.
Usage examples of "angular momentum".
The new hole contains the mass of the holes that went into it, plus the sum of their angular momentum and electric charge.
Their discovery was predicted by Pauli in 1931, because they were needed to preserve the laws of conservation of energy and angular momentum.
Its linear momentum left a hole agape in the stern of the cylinder, its angular momentum left a spin.
What's more, if all the angular momentum of the Earth-Moon system were squeezed into the Earth alone, it wouldn't have enough spin to throw off the Moon.
This theory, like early theories of the solar system's formation, falls foul of angular momentum.
The planet was beginning to move now, gaining angular momentum at a phenome-nal rate.
But now, with the growth of the disk, angular momentum is transferred and the spin slows down!
It is a pairing of angular momentum, in such a way that the total angular momentum of a pair is zero.
The explosion that destroyed the Alberich and killed Alexis and Nita had expelled enough material from the rock to give it some angular momentum.
The launchers stole slightly from its angular momentum, causing it to begin its long sunward fall a few days before it normally would have.
The duck waddle when hurrying arose from the laws of dynamics, from angular momentum, and the engineers were unable to overcome it completely.
He would use the gas giant's gravity to adjust their course, picking up angular momentum in an outbound slingshot.
As its ass is rotating around, she reels in hard, converting that gift of angular momentum into forward velocity, and ends up shooting right past the van going well over a mile a minute.
When Chiron flew by the hole it would need an angular momentum comparable to that of the hole itself.