While recognizing that you need at least three direct shear tests to draw a Mohr-Coulomb failure envelope, you attempt to estimate the equation of the failure envelope through one test. You consolidate a dry sand sample under a vertical pressure of 2000 psf and the shear stress at failure is 1200 psf. Estimate the equation of the failure envelope.

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?