For which one of the following situations would Kendall’s tau be appropriate? a) The Mohs scale rates the hardness of minerals. If one mineral can scratch another, it is judged….

## Calculate the time to dry a batch of this material from X1 = 0.45 to X2 = 0.30 using the same drying conditions but a thickness of 50.8 mm, with drying from the top and bottom surfaces.

Time for Drying in the Constant-Rate Period. A batch of wet solid was dried on a tray dryer using constant-drying conditions and a thickness of material on the tray of 25.4 mm. Only the top surface was exposed. The drying rate during the constant-rate period was R = 2.05 kg H_{2}O/h · m^{2} (0.42 lb_{m} H_{2}O/h · ft ^{2}). The ratio L_{S} /A used was 24.4 kg dry solid/m^{2} exposed surface (5.0 lb_{m} dry solid/ft ^{2}). The initial free moisture was X_{1} = 0.55 and the critical moisture content X_{C} = 0.22 kg free moisture/kg dry solid.

Calculate the time to dry a batch of this material from X_{1} = 0.45 to X_{2} = 0.30 using the same drying conditions but a thickness of 50.8 mm, with drying from the top and bottom surfaces. (Hint: First calculate L_{S} /A for this new case.)