Mass of hot water at 60°C = 40 g Mass of cold water at 20°C = 50 g Mass of vessel = 200 g Suppose the specific heat of vessel is Sv
Heat energy given by hot water = mSw∆T
= 40 × 1 × (60 – 30) [∵ T1 = 60°C, T2 = 30°C]
= 40 × 30 = 1200 cal Heat energy taken by cold water = mSw∆T
= 50 × 1 × (30 – 20) = 50 × 10 = 500 cal
Heat energy taken by vessel = mSv∆T =
200 × Sv × (30 – 20) = 2000 Sv
According to the principle of method of mixtures,
Heat lost by hot water = heat gained by cold water + heat gained by vessel 1200 = 500 + 2000 Sv
