When doing studies with acceleration (inertial forces, i.e., gravity), it seems that there is at least three ways to include a component that you want to assume is rigid:
1. Right click on a part and select "make rigid".
2. Right click on a part and select "remote mass". (Note the performance issues; see https://forum.solidworks.com/thread/27603?tstart=0)
3. Use the workaround I describe in https://forum.solidworks.com/thread/27603?tstart=0 - manually add a remote load/mass to face(s).
Option 1 seems to mesh the part that is rigid. I don't know if it's a shell mesh just to establish the contact with the face, or if it's actually meshing the whole thing. Seems like a waste of processing time to me.
Option 2 seems predictable enough. Aside from the performance issues, the face onto which the remote mass is attached becomes rigid. So I can't see a difference between 1 and 2.
Option 3 also makes the selected faces rigid (to each other). You can try it yourself very easily; make a part that is very weak in the middle and using split lines make two "contact patches" on either side of the weak point, and attach a remote force or mass to these two faces---the weak point is inconsequential.
So can someone tell me what the difference is between these two methods as far as the simulation goes?