A cubical wooden box is hanged in a room by keeping the 15 kg ice in it. Inner length of box is 50 cm and thickness is 7.5 mm. Time taken by whole ice at 0^(@)C to mellt will be. . ..For wood, K=6xx10^(-4)" cal s"^(-1)" cm"^(-1)" "^(@)C^(-1). Outer temperature is 25^(@)C, located heat of fusion of ice is 80 cal/g :

A cubical wooden box is hanged in a room by keeping the 15 kg ice in i

1.	A cubical wooden box is hanged in a room by keeping the 15 kg ice in it. Inner length of box is 50 cm and thickness is 7.5 mm. Time taken by whole ice at 0^(@)C to mellt will be. . ..For wood, K=6xx10^(-4)" cal s"^(-1)" cm"^(-1)" "^(@)C^(-1). Outer temperature is 25^(@)C, located heat of fusion of ice is 80 cal/g :
Answer» 2000 s 2500 s 3500 s 4000 s Solution :Heat TRANSFERRED from cross-sectional AREA A in time t, `Q=KA(((T_(1)-T_(2)))/(L))t` but `Q=mL^(1)` `:.mL_(f)=KA((T_(1)-T_(2))/(L))t` `:.t=(mL_(f))/(KA(T_(1)-T_(2)))` Here `m=15` kg = 15000 g latent heat of fusion `L_(f)=80" cal/g"` `L=7.5` MM `=0.75` cm `K=6xx10^(-4)" cal s"^(-1)" cm"^(-1)" "^(@)C^(-1)` `A=6(l^(2))=6xx(50xx10^(-2))^(2)=6xx0.25` `A=1.5" cm"^(2)` `T_(1)-T_(2)=25^(@)C` `:.t=(15000xx80xx0.75)/(6xx10^(-4)xx1.5xx25)` `=(900000)/(225)` `:.t=4000s`