Changes

The angular momentum of a point mass about a point is defined as '''r''' x '''p''' where '''r''' is the position [[vector quantity|vector]] of the point mass with respect to the point of reference and '''p''' is the [[momentum|linear momentum]] vector of the point mass.

The angular momentum of a point mass about a point is defined as <math>\vec r \times \vec p</math> where '''r''' is the position [[vector quantity|vector]] of the point mass with respect to the point of reference and '''p''' is the [[momentum|linear momentum]] vector of the point mass.

The principle of angular momentum can be applied to a system of particles by summing the angular momentum of each particle about the same point.

The principle of angular momentum can be applied to a system of particles by summing the angular momentum of each particle about the same point.

The [[derivative]] of angular momentum with respect to time is equal to the sum of the external moments ('''r''' x '''F''') applied to the system.  From this, it can be concluded that in the absence of an external moment, angular momentum must be conserved.

The [[derivative]] of angular momentum with respect to time is equal to the sum of the external moments (<math>\vec r \times \vec F</math>) applied to the system.  From this, it can be concluded that in the absence of an external moment, angular momentum must be conserved.

[[Category:Physics]]

[[Category:Physics]]