This issue is related to the anticipated changes and unlikely changes.
It is not clear what you mean by "interact" in AC4. Are you referring to the governing physical equations for interactions between objects (ie, collisions)? If this is the case than I believe that this anticipated change is related to AC10 (or the same as).
Also, I do not think that UC3 is an "unlikely change", it is a goal.
Lastly, UC5 and UC6 don't seem to be related to design. They should be covered by the assumptions in your SRS. @smiths made a similar comment to some of my UCs during my presentation (that they are actually assumptions from SRS) . I think that UC5 and UC6 suffer from this same issue.
Dear @oluowoj
This issue is related to the anticipated changes and unlikely changes.
It is not clear what you mean by "interact" in AC4. Are you referring to the governing physical equations for interactions between objects (ie, collisions)? If this is the case than I believe that this anticipated change is related to AC10 (or the same as). Also, I do not think that UC3 is an "unlikely change", it is a goal. Lastly, UC5 and UC6 don't seem to be related to design. They should be covered by the assumptions in your SRS. @smiths made a similar comment to some of my UCs during my presentation (that they are actually assumptions from SRS) . I think that UC5 and UC6 suffer from this same issue.