A sample of dry sand is tested in direct shear. The shear box holding the sample has a circular cross section with a diameter of 50 mm. The normal (compressive) load imposed is 200 N. The sample...

A sample of dry sand is tested in direct shear. The shear box holding the sample has a circular cross section with a diameter of 50 mm. The normal (compressive) load imposed is 200 N. The sample shears when the shear force is 130 N.

(a) Determine the test normal stress and shear stress at failure.

(b) Determine the angle of internal friction f for this soil.

(c) What is the probable condition of the tested sample (dense, loose, etc.)?