One end of a copper rod of length 1m and area of cross section `4.0 xx 10^(-4) m^(2)` is maintained at `100^(@)C`. Neglecting the loss of heat to the surroundings find the mass ice melted in 1 hour. Given `K_(Cu) = 401` watt/m - k and `L_(f) = 3.35 xx 10^(5) J//kg`.

Answer

B

Explanation

Thermal resistance of the rod,
`R_(th) = (1)/(kA) = (1.0)/((401)(4 xx 10^(-4))`
`= 6.23 K - "Watt"^(-1)`
Heat current `i_(th) = ("Temperature difference")/(Thermal resistance")`
`= ((100 - 0))/(6.23) = 16` watt
Heat transferred in 1 hour.
`Q = i_(th) t = (16) (3600) = 57600 J`
`(i_(th) = (Q)/(t))`
Now, let m mass of ice melts in 1 hour, then
`m = (Q)/(L) = (57600)/(3.35 xx 10^(5)) = 0.172 kg "or" 172 gm`
`(Q = mL)`