For a steel alloy it has been determined that a carburizing heat treatment of 11.9 h duration will raise the carbon concentration to 0.39 wt% at a point 2.1 mm from the surface. Estimate the time necessary to achieve the same concentration at a 6.2 mm position for an identical steel and at the same carburizing temperature.

Amixture of slurry and mud is to be pumped through a horizontal pipe of diameter 500 mm. the fluid behaves as a bingham plastic with a yield stress of 30 pa and viscosity 0.04 pa.s. describe the effects of the shear stress through a transverse section of the pipe by plotting the variation in shear stress and velocity profile: (i) just before the slurry starts to move (ii) as the slurry flows when the pressure gradient is double that in part (i)