Angular Momentum

Angular moment is one of the physical quantities when the particle or an object subjected to rotational motion or revolutionary motion.

Definition for angular momentum:

The definition varies with revolution of a particle and rotation of the rigid object. When the particle revolves in a uniform motion and in uniform radius, then the angular momentum is defined as the product of the mass, velocity and position with respect to its origin. The formula expressed as L = mvr (or) L = pr

Here, 'm' represents mass,
'v' represents velocity,
'r' represents position with respect to its origin.
'p' represents linear momentum which is the product of mass and velocity.

The another definition is when an object is subjected to rotate on its own axis, then the angular momentum is found to be the product of its moment of inertia and angular velocity.

The formula expressed as L = I ω

Here, 'I' represents moment of inertia,
ω represents angular velocity.

Law of conservation of angular momentum:

"The total angular momentum of a system has constant magnitude and direction if the system is subjected to no external force".

Applications of conservation of angular momentum:

• In Kepler's 2nd law of orbital motion:

  The law states that "area swept by the line connecting an orbiting object with centre point is same for any two equal periods of time". As per the kepler's law and law of conservation of angular momentum, the fact found is, if there is any decrease in radius of orbiting object then there is an increasing velocity in the orbiting object.

• Earth - moon system:

  Moon is the satellite of the earth and it revolves around the earth. According to the condition existed that the total angular momentum is always constant, if there is any change in earth's angular momentum, it is compensated by the moon's angular momentum. For example, if the rotational speed of earth is decreased, it is compensated by increase in the revolutionary speed of the moon and this is adjusted by adjusting the distance between earth and moon.