Steam at 120^(@)C` is continuously passed through a `50-cm` long rubber tube of inner and outer ratii `1.0cm` and `1.2cm` . The room temperature is `30^(@)C` . Calculate the rate of heat flow through the walls of the tube. Thermal conductivity of rubber `= 0.15Js^(-1)m^(-1)`(@)C^(-1)` .

Answer

A, B, C

Explanation

Given
`K_(rubber)=0.15J/m-s-^(@)C`
`T_1=120^(@)C` `T_2=30^(@)C`
we know for radial conduction in a cylinder
`Q/t=(2 pi Kl(T_1-T_2))/(In(R_2//R_1))`
`=(2xx3.14xx15xx10^(-2)xx50xx10^(-1)xx90)/(In(1.2//1))`
`=232.5=233 J//s`.