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….

## use the analytical equations for the constant-rate and the linear falling-rate periods with the known total time of 6.0 h.

Prediction of Drying Time. A material was dried in a tray-type batch dryer using constant-drying conditions. When the initial free moisture content was 0.28 kg free moisture/kg dry solid, 6.0 h was required to dry the material to a free moisture content of 0.08 kg free moisture/kg dry solid. The critical free moisture content is 0.14. Assuming a drying rate in the falling-rate region, where the rate is a straight line from the critical point to the origin, predict the time to dry a sample from a free moisture content of 0.33 to 0.04 kg free moisture/kg dry solid. (Hint: First, use the analytical equations for the constant-rate and the linear falling-rate periods with the known total time of 6.0 h. Then, use the same equations for the new conditions.)