Page 38 - FINAL DBS10012_HEAT TEMPERATURE 20102022 (2) (1)
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EXAMPLE 1-4


                      1)  A 0.5 kg of water at 60 °C is mixed with m kg of water at 15 °C. The final temperature

                                                                                                      -1° -
                         of the mixture is 55 °C. Find the value of m? (Specific heat capacity of water is 4200 Jkg C
                         1 )
                                 Solution:


                        Quantity                                Material

                                                                Cold water         Hot water

                        Mass, m                                 m                  0.5
                        Specific Heat Capacity, c               4200

                               -1
                            -1
                        (J kg  °C )
                        Initial temperature, θ1                 15°C                   60°C
                        Final temperature, θ2                                             55°C

                                            Q gained   =   - Q lost
                                        (mc ∆q ) water   = - (mc ∆q ) water

                                       (m) (4200) (55°C -15°C)    = - [(0.5) (4200) (55°C-60°C)]
                                                    m (4200) (40°C)    = - [2100(-5°C)]

                                                            m (168000)    = 10500
                                                                           m    = 10500

                                                                                 168000
                                                    m   = 0.0625kg











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