Liikemäärämomentti

Liikemäärämomentti, often translated as angular momentum, is a fundamental concept in physics that describes the rotational analog of linear momentum. Just as linear momentum is a measure of an object's tendency to continue in straight-line motion, angular momentum quantifies an object's tendency to continue rotating. It is a vector quantity, meaning it has both magnitude and direction.

The magnitude of the angular momentum of a point particle is given by the product of its moment of inertia about the axis of rotation and its angular velocity. For a rigid body, it is the sum of the angular momenta of all its constituent particles. Mathematically, for a point particle, it is often expressed as the cross product of the position vector from the origin to the particle and its linear momentum.

A key principle related to angular momentum is the law of conservation of angular momentum. This law states that if no external torque acts on a system, its total angular momentum remains constant. This principle explains phenomena such as the increase in the spin rate of an ice skater when they pull their arms in or the rotation of a collapsing star.

Angular momentum is crucial in understanding the motion of planets, the behavior of gyroscopes, and the interactions of subatomic particles. Its conservation simplifies the analysis of many complex rotational systems and is a cornerstone of classical and quantum mechanics.