Snow and ice are suddenly removed from the streets of a city. Due to the cold that continues for 60 days, the water pipes passing 1 meter deep from the surface freeze. Since the average temperature of the soil was 5C before the snow was removed, What is the surface temperature? The average properties of the soil can be taken as k = 45 cal/m.st.K, = 1128.6 kg/m3, Cp = 100 cal/kg.K.