How would you add a force to an object such that it moves away from another object?
Assuming you want to move object1 away from objec2. Determine the angle from object2 to object1 (not the other way round). Apply a force on object1 using the aforementioned angle.
If I remember correctly there is a ‘move object towards another’ action. use this and put in a negative value for the speed. I remember doing this once before.