BCC lithium has a lattice parameter of 3.5089x10^-8cm and contains one vacancy per 200unit cells. Calcuate (a)the number of vacancies percubic centimeter; and(b)the density of Li.

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)