What Is the Conservation of Angular Momentum?

The law of conservation of angular momentum is one of the universal laws of physics. It reflects the general law of the motion of particles and points around a point or an axis. Particles and particles equal to zero are the general laws of movement around that point (or axis).

Overview of angular momentum conservation law

One of the universal laws of physics. For example, a particle moving in a centered force field is always subject to a centered force passing through the center of force. Since the moment of the centered force on the center of force is zero, the particle is conserved of the angular momentum of the center of force according to the angular momentum theorem. Therefore, the particle trajectory is a plane curve, and the sagittal diameter of the particle to the center of force sweeps through the same area in equal time. If the sun is regarded as the force center and the planet is regarded as the mass point, then the above conclusion is Kepler planet motion

Angular momentum schematic

Kepler's second law, one of the three laws. For a particle system that is not affected by external forces or external fields, the internal force of the interaction between particles obeys Newton's third law, so the principal moment of the internal force of the particle system for any point is zero, and the angular momentum conservation of the particle system is derived. If the algebraic sum of the moments of the external force system to a fixed axis to a fixed axis is zero, the angular momentum of the particle to the axis is conserved. Conservation of angular momentum is also an important basic law in microphysics. During the decay, collision and transformation of elementary particles, the laws of conservation that reflect the general laws of nature, including the laws of conservation of angular momentum, are followed. W. Pauli speculated in 1931 that antineutrinos were produced when free neutrons decayed according to the law of conservation, which was confirmed experimentally after 1956.

Theorem of conservation of angular momentum

Also called Momentum Moment Theorem.

A theorem expressing the relationship between angular momentum and moment. For a mass point, the angular momentum theorem can be expressed as: The differential of the angular momentum of a particle with respect to a fixed point versus time is equal to the moment of the force acting on the particle with respect to the point. For the particle system, since the internal force of the interactions among the particles obeys Newton's third law, the principal moment of the internal force of the particle system for any point is zero. Using this characteristic of internal force, the angular momentum theorem of the particle system can be derived: the differential of the angular momentum of the particle system with respect to any fixed point O versus time is equal to the vector sum of the moments of the external forces acting on the particle system with respect to O . by

Angular momentum theorem

It can be seen that the angular momentum describing the overall rotation characteristics of the particle system is only related to the external force acting on the particle system, and the internal force cannot change the overall rotation of the particle system.