A composite rod is made from stainless steel and iron and has a length of `0.5` m The cross-section of this composite rod consists of a square within a circle. The square is 1 cm on a side `k_(steel)=14 W//m^(@)` C, `k_(iron)=80 W//m^(@)` C One end of the rod is at `78^(@)` C and other end is in melting ice. Find the amount of ice melted in 7 minutes (in gm). (Take `pi=22//7`)

Answer

`1716`

Explanation

`(dQ)/(dt)=(k_(1)A_(1))/L DeltaT+(k_(2)A_(2))/L DeltaT=(80xx1xx78)/(0.5)+(14xx(pixx(1/sqrt(2))^(2)-1^(2))xx78)/(0.5)`
`=156[80+(7(pi-2))/2]=156[80+7((22-14)/7)]=156xx88xx(dm)/(dt)xxL_(f)=(dm)/(dt)xx80xx4200`
`Deltam=(156xx88xx7xx60)/(80xx4200)=11xx156xx10^(-3)` kg
`=1716` gm