When cartilage is unloaded there is a tendency for fluid to be sucked back into the tissue due to a "Donnan osmotic swelling pressure" from the ionic concentration being higher than the surrounding synovial fluid in the joint. According to the graph showing swelling pressure vs ionic concentration, what is the equilibrium pressure for a normal joint (c=0.15M) ? Since cartilage is biphasic, what is the equilibrium stress in the solid phase? If the tensile modulus of cartilage is E=5MPa, what is the residual (unloaded) strain in the tissue due to swelling? How would the residual strain change if the synovial fluid were replaced with pure water (c =0M)