Pyörimisliikemäärä

Pyörimisliikemäärä, also known as angular momentum, is a fundamental concept in physics that describes the rotational inertia of a body. It is a vector quantity, meaning it has both magnitude and direction. The magnitude of pyörimisliikemäärä depends on the object's mass, how that mass is distributed relative to the axis of rotation, and its angular velocity. Mathematically, for a point mass, it is calculated as the cross product of its position vector from the axis of rotation and its linear momentum. For a rigid body, it is the product of its moment of inertia and its angular velocity.

The conservation of pyörimisliikemäärä is a crucial principle. In the absence of external torques, the total pyörimisliikemäärä of a system remains constant. This means that if an object's distribution of mass changes, its angular velocity must change proportionally to keep the pyörimisliikemäärä the same. A common example is an ice skater pulling their arms in to spin faster.

Pyörimisliikemäärä is essential for understanding the motion of celestial bodies, the behavior of gyroscopes, and the dynamics of rotating machinery. Its conservation explains why planets maintain their orbits and why spinning objects tend to maintain their axis of rotation. It is analogous to linear momentum in translational motion, representing the "quantity of rotational motion" an object possesses.