Question

Is angular momentum a scalar or vector? If it is a vector, what rule is used to determine its direction?

Answer 1

Angular momentum is a vector quantity that represents the product of a body's rotational inertia and rotational velocity about a particular axis. 
The angular momentum is the product of the moment of inertia and the angular velocity around an axis.The units of angular momentum are kg∙m2/s.

angular momentum = (moment of inertia)(angular velocity)

L = Iω

L = angular momentum (kg∙m2/s)

I = moment of inertia (kg∙m2)

ω = angularvelocity (radians/s)