The ladder operators on the spherical harmonics can be constructed from the operators for this quantity'scomponents. Those components do not commute with each other, but do commute with this quantity'ssquare. The subscript in a term symbol gives the total amount of this quantity. The effective potential isequal to a term proportional to this quantity squared plus potential energy. Kepler's second law isequivalent to the conservation of this quantity. In quantum physics, this quantity's intrinsic type is knownas spin. The time derivative of this quantity is torque. For 10 points, name this quantity often calculated as"r cross p," a conserved quantity that measures an 
The ladder operators on the spherical harmonics can be constructed from the operators for this quantity'scomponents. Those components do not commute with each other, but do commute with this quantity'ssquare. The subscript in a term symbol gives the total amount of this quantity. The effective potential isequal to a term proportional to this quantity squared plus potential energy. Kepler's second law isequivalent to the conservation of this quantity. In quantum physics, this quantity's intrinsic type is knownas spin. The time derivative of this quantity is torque. For 10 points, name this quantity often calculated as"r cross p," a conserved quantity that measures an object's rotation.
The ladder operators on the spherical harmonics can be constructed from the operators for this quantity'scomponents.
angular momentum [do not accept or prompt on "momentum"]