Solve Rigid Body Collision: System Approach w/Cons. Angular Momentum

[anandvineet27]

under what conditions can a rigid body collision problem be solved using a system approach, (i.e by using the conservation of angular momentum of the two rigid bodies about some point)
the equation M=d[H]/dt is only valid when M and H are taken about a point fixed in a massless extension of a rigid body or its mass center. Yet for two-body collision problems, I have seen the total angular momentum being conserved about some point,( say, if a ball collides with a rod, then the cg of the rod).Is this approach valid?

 

[tiny-tim]

welcome to pf!

hi anandvineet27! welcome to pf!

torque = rate of change of angular momentum (τ = dL/dt) is valid about any axis

(however, τ = Iα is valid only for an axis through the centre of mass or centre of rotation)

 

[anandvineet27]

only valid about axes fixed in an inertial space.

 

[tiny-tim]

yes