The total vertical normal stress on a certain plane at a given point in a clayey soil stratum is 120 kpa, while the effective vertical normal stress is 90 kpa. the total cohesion obtained from a u triaxial test was 100 kpa, while the total cohesion and total friction angle found using a cu test were found to be 58 kpa are and 20 , respectively. the effective cohesion and effective friction angle of the soil are 40 kpa and 31 , respectively. a foundation to be built nearby will induce a shear stress of 60 kpa on this plane. compute the short term and long-term factors of safety against shear failure for this site.