Aspecimen of dry sand was subjected to a direct shear test. a normal stress of 120.0 kn> m2 was imposed on the specimen. the test was carried out until the specimen sheared, with a shear stress at failure of 75.0 kn> m2. determine the sand’s angle of internal friction.

Amixture of gases consists of 0.4 kg of oxygen, 0.7 kg of carbon dioxide, and 0.2 kg of helium this mixture is maintained at 100 kpa and 27°c. determine: (a) the apparent molecular weight of this mixture the volume it occupies (b) the partial volume of the oxygen, and (c) (d) the partial pressure of the helium