Describe briefly the ways water can be polluted.

For the fin equation described in Problem 6.25, if the units of T, h, P, A, and x are expressed in degree Rankine (R), Btu/hr ft2R, ft, ft2, and ft, respectively, what is the appropriate unit for thermal conductivity k if the fin equation is to be homogeneous in units? Show all steps of your work.

Using area as your variable, suggest ways to cool freshly baked cookies faster.