Asolid steel disc has an outer diameter of 500mm and a constant thickness of 25mm. the disc has 110 steel blades equi-spaced around its outer edge. each blade has a cross-sectional area of 60mm2. the disc is rotating at 1200rpm and the average radial stress is 150mpa. the density of steel is 7480 kg/m3. how long are the blades to the nearest mm?

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