A thermocole cubical ice box of side 30 cm is of thickness 5cm. If 4kg of ice is put in the box, estimate the amount of ice remaining after 6 hours. The outside temperature is 45^(@)C and coefficient of thermal conductivity of thermocole = 0.01 W/mK. Given latent heat of fusion of ice = 335xx10^(3)J//kg.

A thermocole cubical ice box of side 30 cm is of thickness 5cm. If 4kg

1.	A thermocole cubical ice box of side 30 cm is of thickness 5cm. If 4kg of ice is put in the box, estimate the amount of ice remaining after 6 hours. The outside temperature is 45^(@)C and coefficient of thermal conductivity of thermocole = 0.01 W/mK. Given latent heat of fusion of ice = 335xx10^(3)J//kg.
Answer» Solution :AREA of SIX faces of the box, `A=6l^(2)=6xx(0.3)^(2)=0.54m^(2)` thickness, L = 5 CM = 0.05 m, time, t = 6 h = `6xx3600s` temperature difference = `45-0=45^(@)C` Total heat entering in to the box in 6 hours. `Q=(KA(theta_(1)-theta_(2))t)/L=(0.01xx0.54xx45xx6xx3600)/0.05=104976J` If .m. be the amount of ice melted, then `m=Q/L_("ice")=(104976)/(335xx10^(3))=0.313kg` `THEREFORE` mass of ice left after `6h=4-0.313=3.687kg`.