Find the components along the x, y, z axes of the angular momentum l of a particle, whose position vector is r with components x, y, z and momentum is p with components px, py and pz. Show that if the particle moves only in the x-y plane the angular momentum has only a z-component.


From the given data,


Linear momentum vector,


Position vector,


We have, Angular momentum,


=


=



By comparing respective components, we get,





Since, the particle moves in x-y plane, then the vectors of both position and linear momentum vectors be Zero.


Thus,





Hence, the particle moves in x-y plane the angular momentum acts towards z-direction.


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