The following results were obtained from a standard compaction test on a soil:
Mass (g) 2010 2092 2114 2100 2055
Water content (%) 12.8 14.5 15.6 16.8 19.2
The value of Gs is 2.67. Plot the dry density–water content curve and give the optimum water content and maximum dry density. Plot also the curves of zero, 5 and 10% air content and give the value of air content at maximum dry density. The volume of the mould is 1000 cm^3.

At steady state, air at 200 kpa, 325 k, and mass flow rate of 0.5 kg/s enters an insulated duct having differing inlet and exit cross-sectional areas. the inlet cross-sectional area is 6 cm2. at the duct exit, the pressure of the air is 100 kpa and the velocity is 250 m/s. neglecting potential energy effects and modeling air as an 1.008 kj/kg k, determine ideal gas with constant cp = (a) the velocity of the air at the inlet, in m/s. (b) the temperature of the air at the exit, in k. (c) the exit cross-sectional area, in cm2