LinearMomentum[A,B]

A: name of defined observer B: name of defined point

The function LinearMomentum returns the linear momentum of a rigid body with reference point B relative to the observer A.

The linear momentum is expressed using the symbol M for the total mass of the body.

Remember to invoke DeclareStates prior to using LinearMomentum.

Restart;
DeclareObservers[A];
DeclarePoints[A,B];
DeclareTriads[a];
DefineObservers[{A,A,a}];
DefinePoints[{A,B,a,q1,q1+q2,q3}];
DeclareStates[q1,q2,q3];
LinearMomentum[A,B]

$\left\{''Type''\to ''Vector'',''Size''\to 1,1\to \left\{''Coordinates''\to \left\{M{\mathrm{q1}}^{\prime },M\left({\mathrm{q1}}^{\prime }+{\mathrm{q2}}^{\prime }\right),M{\mathrm{q3}}^{\prime }\right\},''Triad''\to a\right\}\right\}$

DeclareStates, LinearVelocity, AngularVelocity, AngularMomentum