The velocity distribution for water (20°C) near a wall is given by u = a(y/b)1/6, where a =10 m/s, b=2 mm, and y is the distance from the wall in mm. Determine the shear stress in the water at y 1= mm.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.