An ice ball of radius a and mass m is placed at 0^@C inside a thick hollow sphere of inner and outer radii a and b whose thermal conductivity varies as k=alpha/r^2, where alpha is a positive constantand r is the distance from centre. The temperature of surrounding is theta_0 and latent heat of fusion for ice is L_f.Then ,time required to completely melt the ice ball is (Neglect the contraction in volume when ice melts into water and any change in thermal resistance due to melting of ice of the system.)

An ice ball of radius a and mass m is placed at 0^@C inside a thick ho

1.	An ice ball of radius a and mass m is placed at 0^@C inside a thick hollow sphere of inner and outer radii a and b whose thermal conductivity varies as k=alpha/r^2, where alpha is a positive constantand r is the distance from centre. The temperature of surrounding is theta_0 and latent heat of fusion for ice is L_f.Then ,time required to completely melt the ice ball is (Neglect the contraction in volume when ice melts into water and any change in thermal resistance due to melting of ice of the system.)
Answer» `(mL_f LN (b/a))/(4pialpha theta_0)` `(mL_f (b-a))/(2pialphatheta_0)` `(mL_f(b-a))/(pialphatheta_0)` `(mL_f(b-a))/(4pialphatheta_0)` ANSWER :D

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