If aluminum is diffused into a thick slice of silicon with no previous aluminum in it at a temperature of 1100°c for 6 h, what is the depth below the surface at which the concentration is 1016 atoms/cm3 if the surface concentration is 1018 atoms/cm3? d = 2  10-12 cm2 /s for aluminum diffusing in silicon at 1100°c.

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.6 m below the tank bottom which is a = 6.7 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute). report your answer in meters to two decimal places.