peteroznewman
Subscriber

Yes, that is correct. Reaction Forces are the forces the floor (not modeled) is applying to the stool to keep it in equilibrium. If the forces are all pushing up, then the stool is stable and there is compressive stress in all legs. If one of the reaction forces is pointing down, that means that leg would need to be nailed to the floor and there are tensile stresses in that leg.