The following expression has been proposed for the heat ux q q q(1) = krT where (::)(1) D Dt rvy (::) is a "convected" time derivative and and k are positive constants. What are the units of and k ? Show that this model is frame indier- ent. Remember that D Dt corresponds to the Lagrangian time derivative, so that D Dt u = @ @t u X = @ @t u X = D Dt u; where D Dt denotes the derivative in the * frame and u is a vector eld