In order to protect eyes from damaging near ultraviolet light (UVA with wavlength of 329 nm), sunglasses are often coated so this light is reflected. The index of refraction of the plastic coating is 1.39, the index of refraction of the glass this coating is placed on is 1.59 and the thickness of the glass is 1.97 mm. What thickness coating should be used

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)