A container of negligible heat capacity contains `1kg` of water. It is connected by a steel rod of length `10m` and area of cross-section `10cm^(2)` to a large steam chamber which is maintained at `100^(@)C`. If initial temperature of water is `0^(@)C`, find the time after which it beomes `50^(@)C`. (Neglect heat capacity of steel rod and assume no loss of heat to surroundings) (use table `3.1`, take specific heat of water `=4180 J//kg.^(@)C)`