A plane wall is cooled symmetrically from an initial temperature of $500$C by jets of $20$C water sprayed on both sides. The convection heat transfer coefficient for the problem is h $=3$ W$/$m$2$K$.$ The wall has thickness $1$ m$,$ density $=1$ kg$/$m$3,$ specific heat c $=2$ J$/$kgK$,$ and thermal conductivity k $=16$ W$/$mK$.$ What is the surface temperature of the wall after $10$ s$?$